I am trying to change out a bad bulb, do I have to remove the windage cover from underneath, or does the lens pop off, or try to access it from the headlamp removal ? ? ? no book no brains ! thanks for any help

And this what year car?

If you have an air dam you can remove it to get to the bulb socket. Check and make sure that the bulb socket is OK on late model GM vehicle.

Was that the front lights or back?