8/19/21
9:00 am

The Practical Guide To Mac Security: Part 20, Erasing Your Mac

Check out the rest of the videos in this special course: The Practical Guide To Mac Security.

If you are going to sell, give away, recycle or pass on your Mac to someone else, you want to make sure you sign out of all of your accounts and completely erase the drive on the Mac.

You can also watch this video at YouTube (but with ads).

Video Transcript: Hi, this is Gary with MacMost.com. This is Part 20 of my course The Practical Guide to Mac Security brought to you by MacMost's great supporters. Go to MacMost.com/patreon. There you could read more about the Patreon Campaign. Join us and get exclusive content and course discounts.
So when it's time to get rid of your Mac, whether you're giving it away, recycling it, selling it, or even giving it to another member of your family, you want to make sure you erase it and reset it completely. You never want to give somebody else your Mac, no matter how much you trust them, with all of your stuff on it. You want to give them a fresh start. It's going to be their Mac. You also don't want to give them a chance to make a mistake that could effect your files, your things in iCloud, and your Settings, and your accounts online. 
To erase your Mac you basically need to go through a few steps. First, make sure you don't need anything anymore. Say you got a new Mac and you use Migration Assistant to bring everything over to the new Mac. Then don't rush it. Wait at least a few weeks. I usually wait a few months. If I don't need anything off the old Mac during that period of time then I'm pretty sure that I've gotten everything off of it. Everything is now on the new Mac and there's nothing left on the old one. I just usually have it switched off in the corner somewhere in a closet during that period of time. Another technique you can use is to make a clone onto an external drive of everything on the Mac. Just have that around for awhile. Hopefully you will never need it and eventually be able to reuse that drive for something else. But in the meantime you have this safety net knowing that you've taken all the files from that Mac and stored them on another drive before you get rid of the Mac. 
Then you want to go through a process of signing out of everything on that Mac. So all of the different accounts. Now if you don't do this usually it's not a disaster. But sometimes it can be inconvenient to not have the Mac signed out of a particular account or store or something like that. 
Then you need to erase the drive completely. This could be a little tricky and a lot of people make a critical mistake here and I'll show you that mistake in a minute. Then you want to reinstall macOS because when you erase the drive there's nothing on that drive anymore. Anybody trying to boot up from that will simple get a prompt to install macOS or perhaps nothing at all depending upon the model. So installing macOS will make it so it's very similar to how when you buy a new Mac. But you want to be careful to not go too far and install macOS and then also sign into your Apple ID or something like that.  So you want to know when the right time to stop is. 
Now it's useful to review Apple's information about this before doing it. One of the reasons is that there are a lot of variations depending upon which Mac you've got, which version of macOS you currently have installed on it. This changes all the time. So doing a tutorial here on exactly what to do isn't going to work because some people will have a different situation and over time that situation and some of the techniques may change. So this page at Apple's site tells you basically what I just said. Create a backup. In other words make sure you have everything you need off of that computer. Then you want to sign out of things like signing out of iTunes, signing out of iCloud, signing out of iMessage. Let's take a  look of some of that right here.
For instance, in the Music app, which is what you would have normally now, not iTunes, you would go to Account and here I've got Sign-in because this is my demo account and I'm not signed in but you would see a Sign-Out here. So you can sign-out from the Music App and that should sign you out of the iTunes Store. You also can go into things like the App Store. In there there's Sign-In and Sign-Out. So you can sign-out of that as well. In System Preferences you can go to your Apple ID and here you could also Sign-Out. You go to Overview, you can see here's the Sign-Out button. So you can sign-out of your Apple ID and iCloud Account which takes care of a lot of things. But you also want to continue to check other things. For instance in the Messages App there's also, under iMessage, a way to sign-out. So you want to sign-out of all those. It's not a huge disaster if you don't because you're going to erase the drive anyway. But it will make things a lot easier for you to sign-out of all of these. 
Apple suggests for older Macs, Intel Macs, that you reset the NVRAM. If you click on this link here it will walk you through the steps. On newer Macs you don't need to do that. But basically it's rebooting holding Option Command P & R down on those older Macs with Intel processors to clear NVRAM.
Unpairing Bluetooth devices is useful because sometimes Bluetooth devices can be stubborn and if you leave them connected to a Mac that no longer exists, you don't have it anymore and you've erased the hard drive, then getting that Bluetooth device to actually pair with something else can be troublesome. 
Then you want to erase your hard drive and reinstall macOS. So, what you want to do is first shutdown your Mac. Shutdown and then you want to reboot it but into Recovery Mode. To do that what you're going to do is you're going to hold down the Command and r key. Now this is specific to the Intel processors. So if you have a newer Mac there's a newer technique. Then you want to restart the Mac. Once you hear the chime you can release your finger off of the Power button but you still want to hold down Command and r until you fully booted into Recovery Mode. Then you can release your fingers off of those keys. Let it finish booting into Recovery Mode. The first order of business is to erase the hard drive. 
To do that go into Disk Utility and then this is where people get it wrong very often. You need to go into the View Menu and you need to Show All Devices. Because otherwise you're looking at just pieces of your hard drive and you can only erase each piece one at a time. You want to erase the entire hard drive. So you want to select the top level there like I have to erase the entire hard drive. Not doing this could leave pieces of your data behind and have basically a drive that's not formatted correctly. Then you might want to give it a name like Macintosh HD to be neat. Then go through the steps to erase the drive. Once you've done that, and it's erased, it might take awhile, then you'll be back here in Recovery Mode and you want to go to reinstall macOS. When you reinstall macOS you're going to walk through the prompts and select the drive to reinstall to.
Now what this will do is it will install everything just like it was a new Mac. You want to stop before you ever enter in your Apple ID or any information. So once it's finished installing you basically are done and you do not want to continue as if this is going to be your Mac. So do not enter in any information that yours. Your Apple ID or anything after it gets to that point to the install. Simply shutdown and your Mac is ready to give to somebody else. When they start it up it will then show them the Welcome Screen and give them the opportunity to enter in their information.
Back at this page here you could see that Apple has specific instructions for erasing and reinstalling your drive. Notice that these steps, the ones I've gone through, are not for the newer Macs with Apple Silicone. You want to use a separate thing for that. Basically just hold the Power Button down and continue to hold it down until you get to the mode where you can choose Options. So you could look here to see the steps for newer Macs and you can see you end up at an Options Button there that you could then go and get into the same Recovery Mode there. Go to Disk Utility to erase your Mac. 
Also these pages have some troubleshooting tips here. Things change with each version of macOS so you may want to review these pages before you go through the process and make sure you're making the choices that are correct for the Mac you have and the version of macOS that's installed.

Comments: 17 Responses to “The Practical Guide To Mac Security: Part 20, Erasing Your Mac”

Lori

3 years ago

Hi Gary, I replaced my iMac going on 3 yrs ago. I just migrated everything from the old iMac to the newer iMac. Then its been sitting in it's carry bag in a closet. Meant to deal with all the details of retiring it, time went by, next thing I know Covid! I didn't go through all this sign out protocol. I'm going to get rid of it and wondering if I do all the "signing out", will that not affect anything on my existing iMac as my Apple ID etc is still the same?
Thanks

Gary Rosenzweig

3 years ago

Lori: Signing out of your Apple ID on your old Mac is exactly what you need to do (first step at least). It won't change anyone on your current Mac.

Jerry Carleton

3 years ago

I have an old iMac running 10.6. I just want to erase the HD. I hold down the command R keys, press and hold the start button but it just opens in the regular mode, not recovery mode. Any ideas
Thanks
Jerry Carleton

Gary Rosenzweig

3 years ago

Jerry: if it is that old, then it doesn't have this functionality. You'll need to use the DVD that came with it. Boot using that DVD and there should be some way to erase.

Russell Tolman

3 years ago

First: Thanks for all the info on Mac Security. Been a Mac user for almost 30 years and I have learned so much watching the Security Info.

I always use Secure Erase with the 3 pass option when erasing HD's and SSD's.
Is doing this over kill or prudent?

thanks.

Gary Rosenzweig

3 years ago

Russell: Overkill with SSDs. And if you were using FIleVault then double overkill. Even with HDDs it is hard to justify it in a world where we hand our credit cards to waiters to pay restaurant bills.

Bill

3 years ago

I have noticed that starting holding down Command and R only works to get the Mac into recovery mode if the Mac was totally off - ie: not just using Restart.

Mayne

3 years ago

Thanks for this series of video's Gary. I held the belief that its not necessary to secure erase SSD's as a-pose to HDD's since its "solid" state and not "bits" that should be overwritten. Until I found how easy you can recover data including "DELETED" pictures and video's from iPhone's which basically are too PCI SSD's. I do not want to mention the apps that can achieve this since it may be ad's. I think its worth the wait to secure erase before selling ESP if you have a HD, i'd do SSD's too.

Gary Rosenzweig

3 years ago

Mayne: Not sure what you saw about recovering iPhone data, but most of the techniques involve getting access to the backup, not finding shadow bits on an erased drive.

Mayne

3 years ago

I know about the backup ones, Im not talking about them. There's a program that actually gets the bits and recovers them easily. Its not fake or a gimmick you literally plug in an iPhone and scan for whatever you have ticked and it'll recover it for you. I tried it myself and it scared the out of me. At least witch HDD you can overwrite .. Not sure if it can recover deleted vids and pics AFTER a factory reset though.

Gary Rosenzweig

3 years ago

Mayne: I still think you are comparing two different things here. Deleting a file and erasing the drive are different. Also, using file recovery for a deleted file where you have access to the drive (know the password so the data in decrypted) is different as well. On the iPhone I don't think someone else could recover a photo like that without first gaining access. On the Mac that would be true too, with FileVault. But also if the drive was erased, not just a single file deleted. Hard to say without knowing more about what software you are talking about.

Mayne

3 years ago

I've been avoiding to post its name cos maybe you won't allow it. Its called Ultdata By TenoShare and I think it's literally the only one I found that can recover video's and images directly from IOS device via lightning cable and its costly too.

Gary Rosenzweig

3 years ago

Mayne: Looking at the instructions, it says the device must be connected, unlocked and that you confirm on the device that the computer is trusted. So you can't use this to get into the data on someone's iPhone unless they unlock it and trust the computer it is connected to. So you can't use this to get access to someone else's data.

Mayne

3 years ago

Yes Gary i'm with you totally understand your point. What im trying to say is that they claim you can get it even after a factory reset.

"High Recovery rate, No Matter Why You Lost It"
"Whether you accidentally delete important data or lose data due to jailbreak, update, factory reset, etc."

So after factory resetting then selling your iPhone your data can be still be RECOVERED.

Gary Rosenzweig

3 years ago

Mayne: I would imagine in that case they would be relying on a backup to get the data back, not directly from the device. Data on your iPhone is encrypted. If you sell your iPhone after a factory reset, or even without a factory reset, the new owner couldn't decrypt the data on the iPhone. If you factory reset your iPhone and wanted to get lost data back, you would use your backup to access that lost data. I'm sure that's what they mean.

Mayne

3 years ago

Makes sense. Alright Gary thanks for clarifying this to me. One more last thing, if I am going to sell my pci ssd macbook pro, you recommend I do not waste my time doing secure erase? I do not mind the time waiting.

Gary Rosenzweig

3 years ago

Mayne: There isn't even a secure erase option for an SSD.

Comments Closed.

The Practical Guide To Mac Security: Part 20, Erasing Your Mac

Comments: 17 Responses to “The Practical Guide To Mac Security: Part 20, Erasing Your Mac”

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