change of account ownership

My dad is the owner of the account. He is older and is not tech savvy. We have had this account since I was 17. I am an adult now, and we want to get separate accounts. HOWEVER, it is MY credit card is linked to the profile because I pay the bill, even though it is in his name. I do not want to be locked out of the account, with my credit card info on his account... So I would like to switch the account into MY name.

How would we go about switching it over into MY name, and giving him his OWN account?