Transferring numbers to a new plan with a twist

I want to transfer my number to a new plan from a plan I have with my family. The account owner is my dad whom I don’t wish to talk to hence the twist. I know this can be done easily online but I don’t have access to the online account. I think he made me an ”authorized user” or something like that but I don’t know if that gives me permissions to go to a store and ask for a new plan and a transfer?