Those pieces are only held on by 3M tape... with that being said, you should be able to get them off with some fish line/ dental floss, a blow dryer and some goo gone. Heat up the part with a blow dryer to soften the tape and then use the fish line or dental floss to get behind the piece and kind of saw the tape off. Then use the goo gone to get the residual tape off. I would highly recommend washing the car afterwards to remove ant goo gone and then wax the places where the pieces were.
Hope this helps..