How to Downgrade From Catalina to Mojave
You will lose files you’ve created since the upgrade if you restore an old Time Machine backup. Connect your backup hard drive to your Mac. Restart (or start up) your Mac while holdingCommand+R. you could release the keys when the Apple logo appears. The macOS Utilities window will open. SelectRestore from Time Machine Backupand clickContinue. When theSelect Restore Sourcewindow appears, highlight your backup drive and clickContinue. input your user password to access your disk (if it’s encrypted)....