Mobile home shower faucets can be removed only by accessing the back of the faucet. The way to get to the back of the faucet is through the wall behind the shower. There may not be an access panel available. If you have to cut a wall open to replace your shower faucet, take the opportunity to install an easy access panel for the next time you need access to the faucet. It will cost little, is easy to install, and will save you time and trouble in the long run.
Turn off the main water supply valve that brings water into the mobile home. Open the hot and cold taps in the faucet and drain the water lines. If you forget this step you will be cleaning up water on the floor.
Locate the access panel in the wall behind your shower faucet and use a drill to remove the screws. The access panel may be glued on. Use a pry bar to gently pry the panel off. If the access panel has been painted over, use a utility knife around the outer edges to cut through the layers of paint before prying. In the event there is no access panel, use a straight edge and utility knife to cut through drywall. If you are installing an easy access panel, cut the wall the same size as the panel with the top edge 4 inches above the mounting of the faucet.
Cover your work area with plastic and a towel to catch any water. Unscrew the water lines counterclockwise. Unscrew the plastic mounting nuts, which should be hand tight. Use a wrench gently if you can't unscrew the nuts by hand. Plastic mounting nuts can be easily damaged by tools. Pull the faucet out of the shower wall from the front.
Install the new faucet by inserting it through the shower wall. Replace the mounting nuts by turning them clockwise and hand tighten. Screw the water lines on the connectors and hand tighten.
Turn the main water supply valve on and check your faucet for leaks. If you find a leak in your connections tighten them until the leak stops. Replace the access panel using a drill and screws or construction adhesive. If you are installing an easy access panel follow the manufacturer's instructions for the installation.