Take the light off the unit and turn it up-side-down. Look for a small circular hole on the bottom side of the light in the orange plastic. The on/off switch is inside this hole. Open a paper clip and insert it into the hole until you feel the click of the button being pushed. The unit only needs to be turned off if you are not using it, i.e. bringing it inside for the winter. To test whether it is on or off, take it into a dark room or closet to see if it is flashing.