I haven't had to deal with this scenario myself so someone else might have some insight but it sounds like your local machine is caching your login.

Might be worth trying this:

• Add a new account to the machine using that email
• Make the account privileges match your current account (also add admin for now).
• Login with the new account.
• This should sync things up again, there is a chance you have lost settings that would normally be remembered as it sounds like the system keys off that name.

To get any files under the other users account back if they are not on onedrive. Do this:

• While logged into your new account
• Open Explorer
• Navigate to the Users folder
• Open the folder of your OLD account
• Windows will ask you if you want to take ownership of the folder, as an admin this should go fine
• You can now copy whatever you need out.

Once you are done you can remove the admin group from your user account if you are the type to keep a separate account for admin stuff.