The two screws that hold the switch in place are Phillips, take them out and the switch comes right off.
The white plate with the contacts on tilts out by releasing one of the clips.
Wipe off the old grease and replace it with fresh Vaseline, none of your di-electric grease please.
The grease goes hard over time and holds the contacts apart.
When you put it back together try to immobilize the wires where they come out of the switch, if they are allowed to bend near the solder joint they soon get brittle and snap.