Make a bootable Catalina drive so you can downgrade from the Big Sur betaIf you're planning to test out the public beta of macOS Big Sur, grab a copy of Catalina first and put it on a bootable installer.
If you are planning to install the public beta of macOS Big Sur, there is one additional set of steps you should follow. You should download a bootable copy of macOS Catalina. This is the easiest way to downgrade if you decide you no longer want to test Big Sur and want to go back to Catalina.
Before you start
How to format your external drive for Mac
How to make your external drive bootable for installing Big Sur
How to use Big Sur as an installer boot drive
Before you start
Before you get started, make sure you have a thumb drive with at least 15GB of storage, or a spare external hard drive (one that you don't use with anything else).
You'll also need to download macOS Catalina from the Mac App Store.
Note: After macOS Catalina has downloaded, it will automatically begin the installation process. Close the installer instead.
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Make a bootable Catalina drive so you can downgrade from the Big Sur beta
