Can I upgrade my iPhone at an AT&T store instead of online?

So I'm eligible for an upgrade from my 4s to a 5s but I was wondering if I was able to do this in a store, meaning just walking in and asking for a new iphone. All I read online was logging into your att account somehow doing it that way. Well I'm not the holder of the account so I don't really want to just go in and do that. However, I have all the necessary information such as account holder name, SSN, and billing address. Can I just walk into an AT&T store and request an upgrade there? If thats possible, does anyone know how its done?

Yes you can upgrade at the store.

But you will need the account holders permission.