The switch has a button on the side of the switch. To remove the knob push button in and pull knob and shaft out of the switch. This will turn the lights on as this is done. Best to disconnect at battery to get voltage off switch. This should be what it takes to get the knob off as that was common on older cars. The button is 1/4 inch dia with spring to hold it out. Should be able to find it on the replacement switch to compare.
