Erase and Completely Reset Your Mac

If you are about to sell or give away an old Mac, it is important to erase it completely and reset it so it is exactly as it was when you first bought it. It is important to remember to sign out and remove all accounts and services first, then erase the drive, and then use Internet Recovery to install its original operating system.

Video Transcript
Something that you may need to do from time to time is to completely clean off a Mac. This may happen if you're trying to resell it or pass it along to somebody else. You want to get all your stuff off there and give them a Mac that's just like new.

So the first thing you want to do when doing that is make sure you are signed out of everything. For instance, look in Messages, look in FaceTime, look in iTunes, look in the App Store. Look everywhere you can think of and sign out and delete accounts.

Go into System Preferences, make sure you've turned off all your iCloud services and you've removed your iCloud account. You can see I've done that here. Nothing there. Under internet accounts make sure you've removed all your internet accounts. You can be signed in for things like Twitter, Facebook, etc. Make sure they're all gone. Go into Mail and make sure they're all gone. Clean everything off.

If you're using Cloud services like for Microsoft or Adobe make sure you are logged out of that. All those applications. Make sure everything's good and you won't have anything hanging around on this machine. For instance, you don't want to have the iMessage system still thinking this machine is something that should be sending messages. You want to make sure you are signed out of everything.

The only thing that you want to keep around is WiFi. You don't want sign out of WiFi because to use the internet recovery function, which is how we are going to clean the Mac off, we are going to have to use the WiFi so we can contact Apple and not only load in utilities that will help us clean off this Mac but then reinstall the system clean and fresh.

So what we want to do now is enter internet recovery mode which will instead of loading the operating system from your drive will actually load the operating system or a simplified version of it from the internet, from Apple so it will allow us then to clean off the drive and reinstall the system.

To do that we are going to restart and when we restart as soon as we hit this button I'm going to hold down the keys Option, Command, and R. That will put us in the internet recovery mode. I'm holding down those keys here and in a second you will see it show that we're doing internet recovery mode. That's what we're doing now. It's going to take awhile for it to load the operating system remotely so it's a good time to get a cup of coffee, have a meal and come back when it's ready.

So once it's done, and it took me about twenty minutes with a pretty fast internet connection for it to load this version of the operating system and present me with this screen.

Once it's done the next step that you want to do is you want to choose from Utilities here Disk Utility. So I'm going to choose Disk Utility and Continue. This will allow me to erase the drive. So I can see here, here's my Macintosh hard drive. This other thing here, this OS 10 base system, that's what it just downloaded. Basically downloaded a temporary version of the operating system for me to be able to do this while I'm not using the hard drive.

I'm going to select Macintosh hard drive and then here I can now erase the drive completely. I can do that by selecting the Mackintosh hard drive under Mackintosh hard drive, the volume itself. Go to Erase. I need to choose Mac OS extended journaled. Then hit Erase. That will completely erase the hard drive while at the same time still remaining here inside this utility since this utility is kind of, you can think of it as running in memory rather than running off the hard drive itself.

Then once it's done erasing I have a completely empty hard drive but I'm still in this special mode where I can do other things. So once the erasing is done I can quit disk utility and it's going to take me right back to the screen here.

Now I can go and select Reinstall OS 10. Now notice it says OS 10 not Mac OS as in Sierra Mac OS but OS 10. That's because when I bought this MacBook it was El Capitan what was the most recent version of the operating system. So when I reinstall the OS it's actually going to reinstall El Capitan from Apple servers putting this machine back into factory original state. I can start that by hitting Continue. Then the process will take a long time to download the operating system, reinstall a fresh copy on this blank disk.

The first screen that I'll see after that is a screen asking me to setup my Mac. You don't want to do anything. You don't want to type anything, you don't want to enter anything. You don't want to click on anything. As soon as you see that screen saying that it's time to setup you're Mac then immediately use Command Q to quit the setup. Then immediately shutdown the Mac. What this does, is basically when you start the Mac up again next time, it will start up in that setup mode which is what you want to happen when you give the Mac to somebody, whether you've sold it or given it away, they'll get it just like they took it home from the Apple store asking them to setup their Mac. It won't have your Apple ID on it. It won't have any of your accounts on it. It'll be just like they bought it and it's brand new.

That's how you want to setup a Mac for selling it or giving it away. Tomorrow I'm going to show you how to do this if you're not actually giving it away or selling it. Maybe you just want to clean it off for yourself or maybe you want to give it to someone who is trusted like a child in your family or sibling or something like that. In that case you may not want to reinstall the original operating system that came with it. You may want to install the most recent operating system, in this case Sierra, and it's a little bit easier to actually do that.

Comments: 28 Responses to “Erase and Completely Reset Your Mac”

    12/7/16 @ 8:16 pm

    I forgot to sign out of everything what do I do now reply as soon as possible please thanks Claire

    12/7/16 @ 8:27 pm

    Claire: Details? Did you give away/sell the Mac? Did you erase the drive first? If not, what, exactly, did you do? How long ago? What things do you use? (iCloud, iTunes, Facebook, etc, etc).
    If you erased the drive then the worst you will have to worry about are just annoyances, like needing to deauthorize and re-login. Things like that.
    But it is always a good idea to change your passwords for everything: Apple ID, FB, everything. You should do that every once in a while anyway, so look at this as a good excuse to prioritize it.

    12/8/16 @ 10:32 am

    Why is it necessary to log out or delete all accounts if you are going to erase the hard drive anyway?

    12/8/16 @ 11:10 am

    Jean-Claude: It is useful to alert those services that you are no longer using that device. For instance, with Adobe, it allows you to install software to two machines. If you don’t sign out, it thinks you are still using that machine for one of the two installs. For iTunes, you have a limited number of “authorized” devices. Deauthorizing will give you back one of those devices. In the past, iMessage has continued to try to send messages to hardware because you never “closed” the relationship between the service and the computer. It only takes an extra minute and is worthwhile to make sure to log out and remove all accounts.

    12/8/16 @ 11:25 am

    I bought a Mac that was still showing the old owner’s Apple ID. Can I use this information to change it to my Apple ID or do I have to have the old users Apple ID password?

    12/8/16 @ 11:32 am

    Jeff: You should NEVER use someone else’s Apple ID. It is a bad idea for your sake, their sake, plus it is pretty much identity theft.
    You should wipe it clean and start fresh. Back up your documents first, of course. Visit the Genius Bar if you want to make sure it is done right.

    12/8/16 @ 11:54 am

    Is it worth going through this for an old MacBook 3, with 3 user accounts, that we have already replaced? It is in a closet and has a battery that will not charge, only works when plugged into power, but has lots of confidential info on it. Other choice is to take it apart and chop it up. We’ve upgraded since then!

    12/8/16 @ 12:02 pm

    If you are never going to use it again, then yes, why not? Especially if you haven’t used it in a while and know that you don’t need anything on there. Erase the drive. Use the “security”options in Disk Utility when you erase it so it overwrites the bits on the drive. Then take it in to be recycled. In that case, no need to go beyond the erasing state and bother with installing an OS.

    12/8/16 @ 12:03 pm

    Gary. My prior Mac Desktop (3 yrs ago) quit running and left me with a screen that looked like a blue striped oxford cloth shirt. Nothing else showing. Mac Genius people said hard drive was “gone.” Been meaning to give to electronics recyclers but concerned about someone being able to retrieve old data: medical – legal. I doubt your proposed erase will work. Suggestions?

    12/8/16 @ 12:07 pm

    Anthony: Can you mount it as a target disk? If so, then you can use Disk Utility to erase the drive. Otherwise, if it is an old Mac with a real HDD, then you can open it, pull the drive, and erase it if you have the proper hardware to hook it up as an external drive. Or, just remove it, recycle the Mac, and throw the HDD in a junk drawer.

    12/8/16 @ 1:29 pm

    Perhaps I was not clear. The person i got the Mac from obviously didn’t clear out everything. i want to upgrade to Sierra and it is showing the former owner’s Apple ID. Is your video instructions what I should do so I can upgrade?

    12/8/16 @ 1:32 pm

    Jeff: So it sounds like the person cleaned off the Mac, but then made the mistake of re-installing the OS using their Apple ID, instead of what I show in this video. I think you can use the technique I show in the next video ( to install Sierra over Sierra, but with your Apple ID. I would definitely backup beforehand and don’t choose to erase the drive (unless you have nothing on it anyway). But I’ve never tried to fix this particular issue in this way, so I can’t be sure it will work.
    If you live close to an Apple Store, it may be worth a visit to the Genius Bar.

    Doris McDermott
    12/8/16 @ 1:59 pm

    Your videos are helpful to many people, but I am an 89 year old who does well with printed instructions. I am sorry printed instructions are not available for all your courses.

    12/8/16 @ 2:03 pm

    Doris: There is a transcript if you would rather read that. But I understand what you are saying. I would look at the computer books available (Amazon or your local store) and maybe find a good Mac book or two.

    Dinesh Taylor
    12/8/16 @ 2:58 pm

    Hi Gary – I have an older MacBook – Model Identifier MacBook 4,1 with a Boot Rom Version: MB41.00C1.B00. I want to clean this laptop up and give it to my grandkid. I Option, Command, R does not restart the machine in the internet recovery mode. I also checked the site for updating the firmware at About EFI and SMC firmware updates for Intel-based Mac computers but no luck. Any suggestions to restart in internet recovery mode? I always look forward to your posts on Thursdays. Thanks

    12/8/16 @ 3:01 pm

    Dinesh: For older MacBooks like that, you need to do it the old way: insert the original DVD that came with it and boot from that. Then erase, reinstall the OS, and upgrade from there. I think you can also use a Snow Leopard install disk to do this, but you’d have to look up information specific to that Mac to know for sure — or just try it. Genius Bar if you can’t figure it out.

    12/8/16 @ 5:35 pm

    Great video sir although I wished you would of explained the “Security options” when erasing a Disk. One of my cousins would want to sell his MacBook Pro that came with Lion 10.7 should he use this way? I mean the next buyer wants the latest macOS which the Mac is capable of running. Why use this over booting from recovery disk instead? I mean upgrading from Lion 10.7 to Sierra 10.12.1 would need alot of GB’s to download, plus an Apple ID which we dont want the next buyer to know?

    Dinesh Taylor
    12/8/16 @ 5:43 pm

    Gary – you are brilliant! I could not find the original DVD however I had the Snow Leopard disk and I tried and it worked. Thank you for your help. Dinesh

    12/8/16 @ 6:00 pm

    Nassar: Right, you don’t want to “purchase” (for free) the OS using your Apple ID. You want him to do it. So he gets to use his ID to purchase and install OS X. And for security options, only if you have a HDD (hard disk). Then go ahead and use the security options which will overwrite the bits.

    Susan Bautista
    12/11/16 @ 7:08 am

    Hi, could I use this for iMac 2009?
    Please help ,thank you.

    12/11/16 @ 7:42 am

    Susan: If your Mac is old enough to have an optical drive, then you probably need to boot with the disc that came with the machine, or a Snow Leopard disc, and do it that way.

    Yvonne Strugnell
    12/11/16 @ 11:47 am

    HELP Help
    Cleaned everything off, except WiFi, and pressed Option, Command, R. Came up in Recovery Mode so went away for an hour or so as you suggested. Returned to find grey screen with black Apple logo and it’s been like that for a couple of hours. What do I do, please?

    12/11/16 @ 1:59 pm

    Yvonne: Wait a bit, especially if you have a slow-medium Internet connection. It needs to run OS X/macOS from an Internet-based drive. So it could take a while. I think it took 20 minutes for me, and I have a very fast connection.

    Yvonne Strugnell
    12/12/16 @ 3:16 am

    Gary, I think that 2 hours is rather long and I can hear no disc activity. I’ve managed to reinstall Mavericks, which it was running, but it’s all still registered to me. As I’m selling the iMac I need to reset etc for the new owner. Had a thought, in your video tutorial you imply that the OS that will be installed is the one that came with the Mac -I think it originally came with Snow Leopard and I’ve got those discs. Should I try to reset using those instead of trying the method above?

    12/12/16 @ 7:35 am

    If this is an old Mac — old enough to have an optical drive, then yes, just use Snow Leopard discs and install from those. And be sure to include those in the sale.

    Yvonne Strugnell
    12/12/16 @ 7:49 am

    Well, I tried it and it worked so now the new owner can start from fresh and upgrade to Sierra if he wants.

    2/18/17 @ 11:37 am

    I did everything that I follow on your video but my mac but it stop with a pic of the world with a “! ” This sign in the center and it says 501OF can you please tell Me what I need to do next ? Thank you.

    2/18/17 @ 12:21 pm

    Jose: seek the firsthand help of an expert. Genius Bar or local shop.

Comments Closed.