Completely wiping and resetting an iMac to its factory settings can be a useful way to improve performance, erase personal data before selling, or troubleshoot software issues. The process involves erasing the hard drive, reinstalling the operating system, and setting up the Mac as if it were brand new. While it may sound daunting, resetting an iMac is actually a straightforward procedure that most users can complete in an hour or two.
Before wiping your iMac, it’s critical to back up any important files, photos, or other data you want to keep. Once the reset process begins, everything on the hard drive will be erased. After backing up data, you’ll boot the iMac into Recovery Mode in order to access the erased utility. Next, you’ll erase and reformat the hard drive, which removes all data and restores the computer to its blank factory settings. With the reset complete, you can reinstall the macOS operating system and apps, create a new user account, and restore data from your backup.
Resetting an iMac to factory settings can offer several benefits. It cleans up clutter and frees up storage space. It often improves performance, since the Mac won’t be bogged down by years of accumulated files and configuration changes. And it allows you to start fresh if you’re passing an iMac on to a new owner. Just be certain to fully back up your data first.
Back Up Important Data
Before wiping your iMac, it’s crucial to back up any important files, photos, documents, settings and applications so you don’t lose data. The easiest way to do this is by using Time Machine or iCloud.
Time Machine is an application included with macOS that allows you to back up your entire Mac onto an external hard drive. To set up Time Machine, connect an external hard drive with at least the same amount of storage capacity as your iMac. Then open System Preferences > Time Machine and select the external drive as the backup disk. Once configured, Time Machine will regularly back up your iMac in the background.
You can also back up important files such as photos, documents, contacts, calendars, and more to iCloud. Make sure you’re signed into iCloud on your iMac under System Preferences > Apple ID. Then you can enable iCloud Drive as well as iCloud Photo Library to sync your files and photos to the cloud. iCloud provides up to 5GB of storage for free, but you may need to purchase additional storage if you have a lot of data to back up.
Before wiping your iMac, double check that your Time Machine or iCloud backups contain the latest data you want to preserve. This way you’ll have peace of mind that your important files and information will be safe during the reset process.
Sign Out of iCloud and Other Accounts
Before resetting your iMac, it’s important to sign out of any accounts you’ve signed into on the device. This includes your iCloud account, App Store, iMessage, FaceTime, and any other Apple services. Here are the steps to sign out of these accounts:
To sign out of iCloud:
- Go to System Preferences > Apple ID
- Click “Overview” and then click “Sign Out”
To sign out of the App Store:
- Open the App Store app
- Click on your profile icon in the lower left
- Scroll down and click “Sign Out”
To sign out of iMessage and FaceTime:
- Go to Messages > Preferences
- Click the “iMessage” tab
- Uncheck “Enable this account”
- Go to FaceTime > Preferences
- Click “Settings”
- Uncheck “Enable this account”
Signing out of these accounts ensures none of your personal data remains on the iMac when you reset it. It also unlinks the device from your Apple ID so it can be used with a new account after resetting.
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Boot Into Recovery Mode
To completely wipe and reset an iMac, you need to boot into Recovery Mode first. Here’s how to do it on an iMac:
On an Intel-based iMac, restart your computer and hold down the Command + R keys immediately after you hear the startup chime. This will boot your iMac into Recovery Mode over the internet and allow you to reinstall macOS or erase the drive. (Apple Support)
On an M1 iMac released in 2020 or later, press and hold the power button after shutting down the computer. Keep holding the power button until you see the startup options window appear. Then select “Options” and click “Continue” to boot into Recovery Mode. (Lifewire)
Once in Recovery Mode, you’ll see the macOS Utilities window. From here, you can proceed to erase the hard drive and reinstall macOS to reset the iMac.
Erase the Hard Drive
The next step is to completely erase and reformat the hard drive using Disk Utility. This will wipe the drive clean and prepare it for a fresh installation of macOS.
To erase the hard drive, reboot into Recovery Mode if you aren’t already there. Open Disk Utility from the Utilities window. Select the internal hard drive from the sidebar, usually named “Macintosh HD.” Click the Erase button at the top of the window.
Make sure the format is set to “APFS” and the scheme is “GUID Partition Map.” You can also enter a name for the drive if desired. Then click Erase to wipe the drive – this may take a while depending on the size of the hard drive.
Erasing the hard drive ensures no leftover files or settings remain from the previous installation. It deletes all data so be absolutely certain you have backups before proceeding. After erasing, the drive will be empty and prepared for reinstalling macOS (Apple Support).
Reinstall macOS
The next step is to reinstall the latest version of macOS on your iMac. To do this, you’ll need to download the macOS installer from the App Store. According to Apple Support, you can download the latest macOS by opening the App Store app while in macOS Recovery mode.
Once the macOS installer is downloaded, you’ll be guided through the steps to install it. Make sure to select your drive and follow the onscreen instructions. The amount of time it takes to install macOS will vary depending on your iMac model and internet connection speed. Just leave your iMac alone until the installation process is fully complete.
Reinstalling the latest macOS will give your iMac a fresh start with a clean operating system install. This should resolve any software issues you were experiencing prior to wiping your iMac.
Create a New User Account
After erasing the hard drive and reinstalling macOS, you’ll need to create a new administrator account. This will give you full access to customize the Mac again.
To create a new admin account:
- Click the Apple menu and go to System Preferences > Users & Groups.
- Click the lock icon in the lower left corner and enter your password to make changes.
- Click the + button below the list of users.
- Enter the Full Name, Account Name, and Password for the new admin account.
- Ensure “Allow user to administer this computer” is checked to grant admin privileges.
- Click Create User.
The new account will now appear in the list of users with admin rights to install software, change settings, and access all files (cite: Apple Support). You can now log in with the new credentials and customize the Mac.
Restore Data from Backup
After reinstalling macOS and setting up a new user account, you can restore your files and data from a Time Machine or other backup. Here are the steps to restore data from a Time Machine backup:
1. Open Migration Assistant on your newly configured Mac. You can find it in Applications > Utilities.
2. Click “From a Mac, Time Machine backup, or startup disk” and select your Time Machine drive.1
3. Migration Assistant will scan the backup and display all the available backup sources. Select the one you want to restore from.
4. Select the files/data you want to restore. Make sure to deselect system files if you don’t want to overwrite your fresh macOS install.
5. Click Continue and Migration Assistant will restore the selected files/data to your new Mac.
You can also restore individual files from Time Machine using Finder. Navigate to the Time Machine drive, enter Time Machine, locate your files, and restore them to your new Mac.
Reinstall Apps
After reinstalling macOS and setting up a new user account, you will need to reinstall any applications you use. This Apple discussion provides guidance on redownloading apps purchased from the App Store.
First, open the Mac App Store and log in with the Apple ID originally used to purchase your apps. Under the Purchases tab, you will find a list of all previously downloaded applications. From here, you can redownload any apps free of charge.
If an app was not originally downloaded from the App Store, but instead purchased as a standalone download from the developer’s website, you will need to visit their site again to redownload the application. You may need to repurchase the app if it was not tied to your Apple account.
Take stock of which third-party applications are mission critical for your workflow, and focus on getting those downloaded and installed first after reinstalling macOS.
Final Steps
After completing the steps to erase and reinstall macOS, there are a few final things you should do to finish resetting your iMac (source):
First, turn on FileVault disk encryption for your new user account to help protect your data. Go to System Preferences > Security & Privacy and enable FileVault. This will encrypt all the data on your startup drive so it is protected if your iMac is lost or stolen.
Next, make sure to check for any available software updates to get the latest security patches and bug fixes. Go to the App Store, click Updates, and install any macOS updates that are available.
You may also want to reinstall any additional apps you need, such as Microsoft Office, Adobe Creative Cloud, etc. Download the installers for your desired apps and run through the installation process.
Finally, consider customizing the settings of your iMac to your preferences. Tweak settings in System Preferences for displays, keyboard shortcuts, trackpad gestures, and more to match your workflow.
Following these last steps will help ensure your iMac is fully protected, up to date, and set up for your personal needs after being reset to factory default settings.