Logging in the phone

I’ve been using this phone from a long time now and once by chance I mistakenly added a wrong Apple ID in the sign in section in settings. I also deleted all the other gmail accounts I logged in with it. As soon as I realized it.. I tried to the register the email in the Apple ID but it didn’t support that Apple ID. Now I want to log back in my old Apple ID and I am unable to remove the id which I put in as a mistake. I’ve tried various different ways to do so, but I was unable to.. everytime i logging it out.. it shows that the Apple ID is either not verified or not valid. I don’t under What to do.. please help me?