Bob, I think you remove the butt plate/pad, and then use a socket with long extension to reach the fastener that pulls stock to receiver flange, at least this has been the way many of my shotgun stocks have been attached.............Don
Bob, what Don says is the way my single shot rifle stocks come off also. I have no idea what your shotgun looks like but most two piece stocks are attached with a bolt thru the tang that is accessed thru a hole behind the pad. The pad is probably screwed on behind invisible holes in the pad that are easily found with a phillips head screwdriver. I use several long extensions with a large screwdriver tipped socket on my rifles. You can shine a light down the hole and see what kind of head the bolt has. Tom