Name: Type the name that you want the disk to have after you erase it.Click Erase, then complete these items:.Select the disk that you want to erase.In this example, Apple SSD is the startup disk: The disk your Mac started up from is at the top of the list. The sidebar now shows your disks (devices) and any containers and volumes within them. Choose View > Show All Devices from the menu bar in Disk Utility.Select Disk Utility from the Utilities window and click Continue.

When you see the utilities window, you have started up from macOS Recovery.Reinstall the macOS that came with your Mac, or the closest version still available. Upgrade to the latest macOS that is compatible with your Mac. Reinstall the latest macOS that was installed on your Mac (recommended). To start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following combinations on your keyboard. Release the keys when you see an Apple logo Command (⌘)-R.You should make sure you have a known good and verified backup before proceeding, this method will erase your data. This is typically used when you purchase your MacBook. MacOS Recovery should only be used when you are instructed to do so.

How to find the recovery key for mac