You dont have to! Just take the screws out that hold your undercarrige thats above your wheel (like in that pictures) so it slides out enough for you to put your hand through to unclip the sidemarkers
Ok after sitting outside in the cold trying to unscrew the under carriage pieces i still can't push the sidemarkers through. I'm convinced they are clipped or screwed on from the inside. Hopefully tomorrow my friend will help me remove the bumper and get down to business.