Email issue: Account already exists

My email account was not retaining my password. I decided to delete the acct and add it back in to see if it would resolve the issue. When I try to add the acct back in, I get a message "this account already exists". But it doesn’t. Apparently something is being retained behind the scenes that I can't see. How do I fix the issue to be able to add the account back in? And any idea on why it wasn't retaining my password to begin with? I would input the password, it would accept it, then when I go back in, the password field would be blank again.