Back up your data
Sign out of iCloud
Sign out of Messages
Sign out of Music, TV, and other Apple services
Turn off Find My Mac
Restart the MacBook
Enter macOS Recovery
For Apple silicon Macs, press and hold the power button until startup options appear, then click Options and Continue
For Intel Macs, restart and immediately hold Command + R
Open Disk Utility
Select the internal drive
Click Erase
Choose APFS or Mac OS Extended as needed
Confirm the erase
Quit Disk Utility
Select Reinstall macOS
Follow the on-screen instructions
Set up the MacBook as new or shut it down for the next user