Turn off the water supply to the shower. You may find the shut-off valves behind the shower wall in the room adjacent to the shower or a closet, or you may have to turn off water at the main house shut-off valve. Turn the shut-off valves counterclockwise.
Place the bathtub stopper in the down position to prevent accidentally dropping the knob-securing screws down the drain.
Find the securing screw on the side of the handle, if you have lever-type handles. Remove the screw with either a Phillips-head screwdriver or Allen wrench, depending on the type of screw head. Pull the handle straight off the plumbing.
Pry the plastic cap on top of the shower knob, if your shower uses cylindrical knobs. There will be a small notch between the cover and the handle in which you can fit a small flat-head screwdriver to pry the cover off the knob.
Turn the screw in the center of the shower knob counterclockwise with a Phillips-head screwdriver. Pull the shower knob straight off the plumbing.