They no longer use in the sense ? how is Apple ID created did they used secondary authentication account in which they set up three answers for security questions , rescue mail address and its password , date of birth or two factor authentication .
If you sign out Apple ID from Mac system preferences > iCloud https://support.apple.com/en-in/HT208242
They can reset the password from this location only , click on forgot Apple ID and password https://discussions.apple.com/docs/DOC-13561
For secondary authentication account they must overwrite the iCloud Keychain verification code before signing out Apple ID if not in records https://discussions.apple.com/thread/8517158 as it will be required by them if they again sign in with their credentials , if they have gifted you the Mac permanently or if you are using the Mac for time being , sign in with your Apple ID and password in the empty fields and set up your iCloud account , its your choice to set up with 2FA or secondary authentication account .https://discussions.apple.com/docs/DOC-13561
Read https://support.apple.com/en-in/HT201065