as Jeff said you need to push that little button and pull.I have found it helped to push the button in then slowly pull the knob out you will feel the release as it engages it may take a few tries until you feel it then keep the button pushed in while pulling.then when you have the rod out it looks as if there is a nut looking piece that holds the switch in. actuality the nut is a bolt for lack of a better word turn it counter clockwise it will undo allowing switch to be removed. it will help to support switch while doing this.goes without saying disconnect the battery first
if original wiring be aware that it will be very brittle the wire itself should be okay but the insulation will fall apart.
