Wiping and Reloading a Mac Computer

If you’ve already upgraded to macOS Monterey:

If you are running macOS 12 (Monterey) continue with Section A below.

If you’ve yet to upgrade to macOS Monterey:

If you are running macOS High Sierra, Mojave, Catalina or Big Sur (or any macOS before macOS 12) please skip to Section B.

Section A: Erase All Contents and Settings - Click the Apple icon in the upper-left corner of your screen, then select System Preferences from the drop-down menu; From the System Preferences menu in the menu bar, choose Erase All Content and Settings:
Erase Assistant opens and asks you to sign in with your administrator credentials. Enter the password you use to log in to your Mac, then click OK; If you're asked to back up your Mac before resetting it, you can open Time Machine and back up to an external storage device. Or click Continue to proceed without making a new backup; Click Continue to allow your settings, media, data, and the other listed items to be removed:
If you're asked to sign out of your Apple ID, enter your Apple ID password and click Continue; Click Erase All Content & Settings to confirm that you want to proceed; Your Mac restarts and shows a black screen or progress bar. If it needs to reconnect to a Bluetooth accessory such as a keyboard or mouse, you might be asked to turn on the accessory. If the accessory doesn't connect within 30 seconds, turn the accessory off and back on. When reconnecting to a Bluetooth keyboard, you're asked to choose a language; You might be asked to select a Wi-Fi network or attach a network cable. To select a Wi-Fi network, use the Wi-Fi menu in the upper-right corner of the screen; After joining a network, your Mac activates. Click Restart; After your Mac finishes restarting, you are greeted with the Setup Assistant as if you're powering on your Mac for the first time.

Section B: Use Disk Utility to erase your Mac - Start up from macOS Recovery: Turn on your Mac, then immediately press and hold these two keys until you see an Apple logo or other image: Command (⌘) and R; If asked, select a user you know the password for, then enter their administrator password; From the utilities window, select Disk Utility and click Continue:
Select Macintosh HD in the sidebar of Disk Utility; Click the Erase button in the toolbar, then enter the requested details (Name: Macintosh HD Format: APFS or Mac OS Extended (Journaled), as recommended by Disk Utility); Click Erase. However, if you see an Erase Volume Group button, click that button instead.
If asked, enter your Apple ID. After the erase is done, select any other internal volumes in the sidebar, then click the delete volume (–) button in the toolbar to delete that volume (During this step, disregard any internal volume named Macintosh HD or Macintosh HD - Data, as well as any volumes in the External and Disk Images sections of the sidebar); Quit Disk Utility to return to the utilities window; If you want to start up again from the disk you erased, select Reinstall macOS in the utilities window, then click Continue and follow the onscreen instructions to reinstall macOS.