Remove Broken Shower Pipe How To Remove Shower Brass Bonnet?

How to remove shower brass bonnet? - remove broken shower pipe

I have a Delta Monitor 1700 Series (one handle to control the data flow and high temperature) manage controls in order to) the shower (no bathtub. The shower head and sometimes administration of the leak, so I try to take everything apart. The problem is that not even move the brass hood. I have tried to block a key channel, but I come to the point where I wonder if the fraction of water and nothing happens. Ideas?