Shared id problem

My wife turned in her work phone and bought a new one with a new number. The old number is still tied into her personal id number. This is creating problem with texts etc. going to the old number. I can't access the cloud since the two factor identification is going to that number. Pretty much anything to do with apple is locked out to us. Her id is her personal email. Her phone back up goes to the cloud we can't access. Need help with this one.