Apple ID Loading forever, unable to Sign Out of iCloud account

Apple ID is stuck on Apple ID Password dialog, "To continue, enter the password for "...". It has a place for password and a Cancel button. Doesn't matter what I do I will eventually get a spinning thingy and a "Loading..." message forever. It's trying to use the wrong account user name. I'm unable to sign in or sign out. I'm unable to sign in because I forgot the password for the account (I created a new one a few years back?) and iCloud/Apple ID won't let me change it to the same account that purchased the machine with. How do I get past the "Loading..." forever screen so I can change my iCloud account on this Mac. I can use my proper iCloud account when I purchase apps. I just can't use it in Apple ID because the account name is wrong there and I can fix it due to "Loading..." forever.