Back up your data with Time Machine or another backup method
Sign out of iCloud
Sign out of iMessage
Sign out of FaceTime
Sign out of Music, TV, and App Store if needed
If using macOS Monterey or later on Apple silicon or T2 Mac, open System Settings or System Preferences
Go to General
Select Transfer or Reset
Choose Erase All Content and Settings
Follow the on-screen prompts
Enter your administrator password when asked
Confirm the erase process
Wait for the Mac to restart and erase itself
If your Mac does not support Erase All Content and Settings, restart into Recovery mode
On Apple silicon, press and hold the power button until startup options appear, then choose Options
On Intel Mac, restart and hold Command and R
In Recovery, open Disk Utility
Select the startup disk
Click Erase
Quit Disk Utility
Choose Reinstall macOS
Follow the on-screen instructions
After reinstalling, set up the Mac or shut it down for the next user