You'll see the MacOS Utilities window choose 'Disk Utility.' Now you can choose to erase your startup drive, and choose 'Mac OS Extended (Journaled)' as the operating system. To get around that problem, hold down the Command + R keys when you turn on your Mac and let go when the logo appears.

If you want to format your Mac's system drive, you can't do that when the Mac is running normally because the drive is in use by the operating system. Usually, you'll want ExFAT, which is the default for the MacOS.

You can also open Terminal using Spotlight search (Command + Space).

Release the keys once you see the Apple logo or spinning globe. Open up Terminal on your Mac from Applications > Utilities in Finder. Select the drive you want to format and then choose “Erase.”Ĥ. At the top of the window, click 'Erase.'ĥ. In the pop-up window, choose the file system you want to use. Once you’ve backed up your Macintosh HD by using Time Machine, perform the following steps to format your startup disk and reinstall macOS: Step 1: Restart your Mac and immediately press and hold Command + R keys.

Formatting disk mac