How to reset a Mac

Whether you’re giving your old Mac to a friend or family member or selling it online for a bit of extra cash, you’ll want to reset your Mac before you get rid of it. Resetting a Mac will remove all your photos, videos, apps and just about everything else you’ve saved on your machine, allowing the new user to set it up as a brand-new machine. The other benefit, of course, is that you can sell on your Mac without the worry of somebody accessing your data. 

It’s a relatively simple process to reset an iPhone or iPad, but the same can’t be said for Mac. It’s not a simple one-click solution, but where there’s a will, there’s a way. We take you through the process of resetting a Mac right here, from backing up your data and signing out of services like iCloud to wiping your hard drive and reinstalling a clean version of macOS.  

Step 1: Back up your Mac

Resetting your Mac will delete all your documents, data and settings, so it’s a good idea to back up your Mac before resetting – especially if you want to continue to use macOS on another machine. There are paid apps that’ll clone your drive, but if you’re not looking to part with any cash, Apple’s built-in Time Machine functionality should do the job – you just need an external drive to get started.

1. Plug in your external hard drive.
2. You should see a prompt appear, asking if you want to use the drive as a backup drive – click Use as Backup Disk. Note: you won’t be able to use the drive for anything else while it’s used as a backup drive.
3. If the prompt didn’t appear, click the Apple logo in the top left and select System Preferences > Time Machine. Click Select Backup Disk, and select the drive you just plugged in. 
4. You’ll then be asked to reformat your hard drive, deleting any existing data. Click Erase to continue. 
5. Once set up, your Mac will start the Time Machine backup process – if it doesn’t automatically, click Back Up Now in the Time Machine menu. It’ll likely take a while the first time around, so we’d recommend going for a cuppa while it does its thing. 

Once complete, you’ll have a comprehensive back up of your entire Mac, including not only documents and data but all installed apps and system preferences too. 

Step 2: Sign out of iTunes, iCloud and Messages

Once you’ve created your backup, the next step is to sign out of the various Apple (and third-party) services you use on your Mac, especially if there’s a limit on how many devices can access the service at any one time – iTunes can only be used on up to five machines per account, for example.

It also helps to keep things tidier in iCloud, as even though you’ll be resetting your Mac, there’s no way to ‘tell’ Apple and other service providers that this is the case, and they’ll likely still count the existing machine as a device, even if it has been reset and sold.  

iTunes (macOS Mojave or earlier)

Though it’s no longer a part of macOS with the release of Catalina, iTunes is still an integral part of older versions of macOS and Mac OS X.

In iTunes 12:

1. Open iTunes.
2. Click Account > Authorisations > Deauthorise This Computer. 
3. Enter your Apple ID.
4. Click Deauthorise to complete the process.

In iTunes 11 or earlier:

1. Open iTunes. 
2. Click Store > Deauthorise This Computer. 
3. Enter your Apple ID.
4. Click Deauthorise to complete the process. 

iCloud

Next comes iCloud, removing access to your photos, videos and other files stored in the cloud. 

1. Click the Apple icon in the top left and select System Preferences.
2. Click iCloud.
3. On macOS Catalina, select iCloud in the side panel and uncheck Find My Mac if enabled. Then select Overview in the side panel and click Sign Out.
4. On macOS Mojave or earlier, simply click Sign Out from within the iCloud menu. 
5. You’ll be asked whether you want to keep a copy of your iCloud data on your Mac – as you’ll be wiping the hard drive anyway, you can click Keep a Copy to speed the process up. 

Messages

Finally, it’s time to sign out from the Messages app.

1. Open the Messages app.
2. Select Messages in the menu bar, and click Preferences.
3. Click the iMessage icon.
4. Click Sign Out. 

Step 4: Wipe your drive

Once you’ve backed up your important data, signed out of iTunes, iCloud and any other services you use on your Mac, it’s finally time to wipe the drive. 

1. If your Mac is powered on, turn it off.
2. Turn on your Mac and immediately hold down Command + R, and continue to do so until you see an Apple icon appear on-screen.
3. Log in to one of the Admin accounts on your Mac.
4. Select Disk Utility from the Utilities window. 
5. Click View > Show All Devices to display your disks and any containers or partitions within them in the sidebar.
6. The disk at the top of the list is the one that your Mac uses to start up – click it. 
7. Click Erase and input a name, select the format (we’d recommend APFS if you’re running High Sierra or later or Mac OS Extended if you’re running anything earlier) and a Scheme – select GUID Partition Map. 
8. Click Erase to begin the process. You’ll be prompted to enter your Apple ID at this point if you didn’t sign out of iCloud and disable Find My Mac in the earlier steps. 
9. Repeat the process for any other internal drive. 
10. Once complete, quit Disk Utility to return to the macOS Utilities menu.

Step 5: Reinstall macOS

You’ve wiped your hard drive, but you’re not free to sell or set up your Mac just yet – the last step is to install a clean version of macOS. If you don’t do that, your Mac won’t do anything when you turn it on!

1. From the macOS Utilities menu, select Reinstall macOS. 
2. Click Continue and follow the on-screen instructions.
3. Select the drive you wiped in the last section, and click Install. If you’re given a choice between Macintosh HD and Macintosh HD – Data, select the former. 
4. Go and make another cuppa – this one will likely take a while. 
5. Once complete, you’ll see the Welcome screen. At this point, macOS has been reinstalled and is ready to set up. If you’re selling the Mac, you can turn off the Mac at this point. 

For more handy Mac tips, take a look at how to downgrade from macOS Catalina, and how to use an iPad as a second display too.