Get rid of Old Apple ID on my Mac
I have an aging MacBook and I need to update the operating system. I have an old appleID on the computer that was set up with an email address that no longer exists. How do I get rid of the old appleID in order to use my current Apple ID so I can back-up to the cloud and install a more current OS?
thanks for any help!
MacBook Pro 15″, macOS 10.12