

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 select a new backup disk that’s not already formatted as an APFS disk, you get the option to erase and reformat it. APFS or APFS Encrypted disks are the preferred format for a Time Machine backup disk. 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. If you connect a disk formatted for Windows, it can be reformatted (permanently removing all data) to a Mac format and used as a backup disk.

Usually, you'll want ExFAT, which is the default for the MacOS. 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.
