How to Reinstall macOS
1. Start up from macOS RecoveryTo start up from macOS Recovery, turn on your Mac and immediately press and hold one of the following combinations on your keyboard. Command-R is generally recommended, especially if you never installed macOS Sierra 10.12.4 or later… How to reinstall macOS – Apple SupportCommand (⌘)-RInstall the latest macOS that was installed on your Mac.Option-⌘-RUpgrade…