Reach under the headlight switch and feel for a projection. Press the projection upward and pull out on the headlight switch knob. The knob and shaft should come all the way out of the switch.
If you need to remove the headlight switch for service, remember to disconnect the battery ground wire. Use a spanner wrench or a pair of pointed long nose pliers to remove the threaded central portion of the headlight switch bezel.
Installation consists of remounting the switch to the bezel and inserting the knob/shaft into the switch completely. Pull out on the headlight knob and it should remain attached to the switch when pulled out to the headlight on position. Return the switch to full in position. Now reconnect the battery ground.