You will have to Unscrew the Switch. Make sure to have a Rag Ready. The Switch is under Pressure, so it will purge (or should I say Spray) the brake fluid that is in the line. Not a big deal, just be prepared.
Yep I went thru this same ordeal. Best thing to do is pump your pedal (with the ignition off) until the pedal gets hard...it may take 10-15 pumps (mine took 15) and then once the pressure is out grab a wrench and unscrew the switch. And as mentioned have a rag ready, and some splash proof safety goggles too.
Parts swapping on the PowerMaster can be cumbersome and expensive if you don't know you are swapping known good parts. Not to mention that switch and some other parts are pressurezed at over 650psi. Pump the pedal as previously mentioned. It's the proper procedure. Be careful with pliers on that switch. The can be damaged easily. They are made for a socket...if you have the right one.
