Back up your files to iCloud, an external drive, or another storage service
Sign out of iCloud, Messages, and any other Apple services
Turn off Find My Mac in System Settings or System Preferences
Shut down your MacBook Air
Turn it on and immediately press and hold Command + R until the Apple logo or recovery screen appears
If using an Apple silicon MacBook Air, press and hold the power button until startup options appear, then select Options and Continue
Open Disk Utility from the recovery screen
Select Macintosh HD or the main internal drive
Click Erase and confirm
Quit Disk Utility after the erase is complete
Select Reinstall macOS from the recovery screen
Follow the on-screen instructions to complete installation
Set up the MacBook Air as new or restore from a backup
If needed, use Apple Configurator or contact Apple Support if recovery mode does not load