You're all set to fix that leaky shower. You remove the cover and get to the stem, only to find that the locknuts are buried deep beneath the wall covering. It's not impossible to remove if you know what the right tools are.
Turn off the water before beginning any plumbing project. Turn the faucet on to drain any water that remains in the pipe. Once no more water comes out, you are ready to begin.
Pop off hot and cold plastic caps if the screws are not already showing.
Remove the screws and take off the handle or knob. Remove the sleeve that covers the stem.
Check to see if lock nuts are exposed. If they are behind the wall, recessed, a special tool will be necessary for their removal. You should have a five-piece shower valve wrench set, so you know you have the right size for the recessed nut. The wrenches made for this job should be of longer length so that they fit behind the wall and over the lock nut on the stem.
Slide the shower valve wrench of appropriate size over the stem and push the handle of the wrench to one side so that you have more leverage. Turn until it is loose enough to remove.
If the lock nut is difficult to turn, apply a lubricant like WD-40, Kroil, or Liquid Wrench. Use a can that has the thin straw-like spray attachment to reach back to the problem area. Let this soak in for a few minutes after spraying before trying to loosen again. The steps will work for a double handle faucet. The special tool necessary for a single handle faucet like a Moen, or plastic and brass cartridge stems would be a stem and cartridge puller.