I can't reset my Mac because Mac keeps asking me "Sign Out of Find Me" for my old Email ...

I am trying to reset my Mac, but my Mac won't let me because it keeps asking me to enter the password to my old email that no longer associated to my AppleID.

The situation is I have updated my AppleID earlier in the year with a different email (new email that is Current) and updated to a new password too. So my old email, that Mac is asking me password for, firstly the emai no longer associate with my Apple ID and my old password, I don't remember anymore. There is a red font that also says "The operation couldn't be completed. (AKAuthenticationError error -7003" and no matter how many times I do this, in the end, the message also says the email does not exist (old email). So why is Mac still asking for my old email? I am having a whole lot of weird things happening with my Mac and the last thing I want to do is reset it to start it again fresh. I hope someone can help me on this please. In summary with email the response from apple is "This apple ID is either not valid or not supported ......."