Read this to learn how to fix a dripping shower
This is for showers with a cartridge-style faucet. The first thing needed is to replace the old cartridge with a new one.
Remove Handle Cap
Turn off the water supply to the shower. Try turning the shower on to make sure it's off. Then, pry open the handle cap.
Remove the Handle
Take out the screw in the handle, then remove the handle and set it aside.
Pry Up the Retaining Clip
Pull off the stop tube and pry up the cartridge retaining clip. Remove the washer and twist the cartridge stem loose and pull it out
Pull the Cartridge
If the cartridge is stuck, you need a special puller. Unscrew the hex screw & nut until the threads are visible. Slide the puller over the stem, aligning the tool "ears" with the cartridge notches, then twist.