Unable to inactivate an emailing settings

The email is an old college email that no longer works, but I still have messages I’d like to be able to keep (they are still visible in my mail). I’m not able to “re enter password because the account is now locked

This second email is how I want the first to show up (this inactive email is another old email that is now closed as well)

Deactivating the email seems to be the only way to stop getting this notification every time I open my mail app