Do you mean joystick or joypad actually? If you mean joystick (since I don't know about the pads) just gently peel away the foam pads, then the adhesive discs sticking them to the Neo, and with a screwdriver, you can break down the j-stick into lots of separate bits.
On one of my old-style sticks, the B-button actually came right off! and was moving around inside the joystick casing.