This guide will show you how to properly remove most of the buttons from the controller. You may want to read this if your buttons are sticky
Place the controller (buttons down) on a solid surface.
Remove the six 9.2mm Tri-wing Y0 screws that hold the back panel in place.
Gently lift the back panel up, separating it from the front panel.
Grab the Z-button by the peg with tweezers and lift it out of the controller.
Carefully unhook the cable that is looped around the peg.
Lift the circuit board out of the controller.
Remove the rubber backing that covers the buttons.
Use tweezers to lift buttons out of their sockets.