Sometimes there's a place you can poke a wire in and release the terminal, other times it's crimped to a contact inside the switch. Don't try to take the switch apart, it's likely to go BOING! and you'll never get it back together right again. Just cut the wire off far enough from the switch that you can splice it using the method of your choice. Crimp butt splice, crimp cap, wire nut, solder and heatshrink, just whatever you're comfortable with that will fit in the space.