Loosen and remove the retaining screws from the lock box on the inside surface of the garage door opposite of where the T-handle is mounted with a Phillips screwdriver.
Slide the lock box off the square shaft protruding through the garage door from the T-handle. Slide the lock box downward and away from the protruding end of the T-handle retaining screw.
Remove the T-handle retaining screws from the outside of the door with a Phillips screwdriver.
Slide the T-handle straight out from the garage door and remove it.