Some have a clamp on the throttle body that needs to be loosened and some don't. Some will come off with a firm pull toward the front of the truck and some have two bolts located at the base on either side of the box.
i just did mine today there is 2 bolts one on each side and a clamp on the back you need to take the 2 bolts out and lossen the clamp then pull to the front of the truck and up at the same time it will come right off