I would simply cut the CA hinges close to the leading and trailing edges on both the rudder and elevator with a sharp #11 blade. Create new slots as close to the old as possible, install the joining wire and reinstall the elevator and rudder using new slots.

I have replaced ailerons on different planes and the procedure works fine. Trying to remove the hinges would cause considerable damage to the wood and probably comprise the reinstallation.

DaveB