Determine which kind of light switch extender is in use. A snap-on extender will have no screws and you can simply pull off the extender. You'll need a screwdriver to remove a screw-on extender.
Turn the room's electricity off at the circuit breaker.
Apply two strips of masking tape to the wall plate to hold it in place.
Unscrew the top and bottom screws from the wall plate using a Phillips screwdriver.
Remove the extender from the switch.
Attach the original wall screws using a Phillips screwdriver. You can purchase replacement screws if the originals are missing. Tighten the screws to prevent the wall plate from falling.
Remove the tape. Turn the electricity back on and test the switch to make sure it is properly working.