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

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.