They can be damnably difficult to remove, especially when both you and they are cold. The business end of the guide which is inserted through the fender is split into two pieces that flair onto the underside of the fender. I've removed it by using a screw driver and pushing one side towards the other whilst pulling on the guide. Sometime back someone mentioned using a strategically sized socket that draws the split pieces together whilst pulling on the bracket. Word to the wise....leave the
things off.