Turn the top of the mouse so the main buttons and wheel are facing you.

Remove the four wide Phillips screws holding the mouse buttons to the top chassis.

Insert a plastic spudger between the left side of the left mouse button and the chassis. Gently pry the button to free it. It should pop off, but may require a light push to the right to fully separate.

Grab the right mouse button to the left of the mouse wheel. Pull it to the left and away from the chassis.