If the large Torx bolts have been removed as you state, be sure you removed the correct set of "bolts" from the wheel well. The ones that matter are the ones that are near the top of the wheel well. To be safe, it wouldn't hurt to remove both per wheel well.

If the correct securing hardware has been removed, you may need to lift your bumper upward to "brake" it free. I had to do this when installing my Hitch.