Those Moen Cartridges can be a real pain to remove, that’s for sure!!First off, we’ll assume you’ve removed the retaining clip from in front of the cartridge.If you’ve purchased a new cartridge you’ll see that there is a white plastic part on one end of the new cartridge. Remove it and place it on the old cartridge. This plastic part has a square end on it. Using a crescent wrench on this plastic piece, turn the old cartridge back and forth until the old cartridge is loose enough to remove. Once it’s removed, insert the new cartridge into the valve body and use that same white part to push it into the valve body. Make sure you reinsert the retaining clip.Good luck.