you have to cancel your reservation through CRO and book through AAA.
If it is room only you may just be able to ask for the AAA discount though.
If it is a package then you have to go through AAA. I would call AAA and make sure there are rooms avalible first so you dont cancel your room and then not be able to get the same room again.
edited to say you will get your room deposit credited back to you and have to put a new one down if you re book with AAA