Hey there. I am currently taking the Apple Device Support course, and I would be happy to assist you!
Your MacBook Air model will determine how to remove the Apple Account. For example:
* MacBook Air 2008 - 2017
* MacBook Air 2018 - 2024 (Retina)
If you have a 2008 - 2017 MacBook Air, follow these steps:
# Go to System Preferences > Apple ID (on older macOS Versions, go to System Preferences > iCloud)
# Click Overview > Sign Out (on older macOS Versions, click Sign Out)
# You can choose if you wish to keep a copy of certain iCloud files
# You must enter the Apple Account password to turn off Find My
# Done
Alternatively if the device belonged to someone else, you can erase the drive and reinstall macOS. If you do not know how to do this, simply let me know!
If you have a 2018 -2024, the steps listed above are the only way to remove the Apple Account. If you erase the drive, the Mac will lock itself to the original owner, making it completely unusable. This lock is known as Activation Lock.
Hopefully this is helpful, and please let me know if you have any other questions!