I'm trying to replace my 20 plus year old delta shower single level faucet. I've removed the lever handle, and unscrewed the backplate. I'm uncertain how to remove the the center portion that will give me acess to rough plumbling. Unless it is on bottom, I see no evidence of a hex screw to remove. I've tried to slide it off and used my large plyiers to try and unscrew it. I did not want to break it, so I left it alone. Is this enough information for anyone to provide any suggestions on my next step.