Here is what I do when I build with a Sanwa on my 360 controllers.
I cut the post that is the ground. You can tell when you look at the solder side of the PCB, it's the area around the outside each switch has one post going to. Unsolder the post, then cut it, pulling out the remainder from the pcb. Then put a dab of glue on the switch to the circuit board as it will become a bit loose with that connection gone.
Then solder, you are good to go.