Unlink Google authentication

[supermathie (Michael Brown)]

Please see this topic for an explanation of the likely problem and a workaround:

Issue: user changed google account and can't connect thru his profile

I have one very active user on my discourse. Everything was fine until a moment when user changed surname and changed his email account. He logged on to discourse thu google authorisation. He changed his email in profile however linked google profile is pointing to an old google account and therefore he got 500 error as in profile email is new but linked google profile is pointing to an old email . How to overcome this issue?