Select Mac OS Extended from the format list.If you have more than one external drive with the same name, you will need to rename the drive you are using as a bootable installer now. Note the name of your external hard drive (probably 'Untitled') because you will need it when you create a bootable drive.Select your thumb drive or external drive under External.Ĭlick on the Erase tab at the top of the window.
Scroll down and double-click on Disk Utility. Select Applications from the list on the left side of the window.
You'll need to start with a clean thumb drive or external hard drive to make it a bootable drive. How to format your external drive for macOS Big Sur
