take it off, get some saw horses and a hair dryer and warm up the bumper and slightly mold it back and into shape. mold out the damage spot best you can, (dont get the bumper too hot or youll damage that or the paint) and get it back into shape. Behind the top quarter panel part is a plastic clip, orderable online which should snap & bolt into the quarter panel and let the bumper snap back into place.
https://www.carparts.com/details/Toy...E&gclsrc=aw.ds