MacBook Turned into Former Employer....now he wants my Apple ID?

You need to do this before giving the computer to your employer: What to do before you sell, give away, trade in, or recycle your Mac - Apple Support

All data associated with the computer will be removed.

Do not reveal your Apple ID and password.

If your former employer wanted to control the computer's configuration and content they should have created a MDM profile rather than having you configure the computer as though you were its owner.

Secondly, you should not have used your workplace computer for personal information and activity.

As long as you have not locked down the laptop with your AppleID, then just make sure you have removed that laptop from FindMy. So long as the employer can reinstall macOS onto it & your AppleID is no longer tied to the laptop, then you are good and your former employer should be happy.

If you happened to have locked down the laptop, then the former employer may not be able to unlock the laptop to reinstall macOS without your assistance. If this is the case, then you may need to meet with the former employer & perform the steps listed in the Apple link @BobTheFisherman provided.

Your employer, or anyone who tries to "take over" that Mac cannot update the MacOS or other Mac App Store software without doing one of two things:

• nagging you for your Apple-ID and taking over everything (including that Apple-ID account and your contacts and passwords and anything else you linked to it)

• re-installing the original "shipped in the box" software, supplying a different Apple-ID, and upgrading from there. By design, this is intended to not remove the User files.

Does your Apple-ID still have your payment method connected, your bank account or credit card linked?

Hi,

I think it doesn't hurt anything if you disconnected Apple ID from MacBook, though you should taking backup of password and keychain, iCould mails on iCloud Drive before disconnect your Apple ID from MacBook.