Turn off the shower water supply with the water valve located in the enclosure behind the shower bay. You can usually find the enclosure in the room adjacent to the shower on the shared wall between the two rooms. Turn on the shower and allow the water remaining in the pipes to run out before disassembling the faucet.
Place the tip of a flathead screwdriver beneath the small handle cover on the faucet and pry it from the faucet top to reveal the faceplate screws holding the handle disc in place.
Use a Phillips head screwdriver to remove the faceplate screws from the handle disc. Pull the handle disc away to access the escutcheon plate against the shower wall.
Cut through the caulk around the escutcheon plate’s base against the wall with a putty knife, and then pull the caulk away with the knife’s tip. Pull off the escutcheon plate.
Remove the handle washer from around the handle base within the wall opening. Remove the handle o-ring, followed by the stem o-ring and stem stop from around the base of the faucet stem.
Unscrew the three cap screws on the base of the mixing cartridge. Pull the cartridge from the integral stop stem assembly lying against the shower pipes. Remove the sealing ring for the cap and then unscrew and remove the stop assembly to complete the disassembly and removal of the Sterling shower faucet mixing valve.