I have a 2002 Chevy Siverado Truck, 2 door. I'm replacing my headliner and I'm having all kinds of trouble figuring out the removal of the garment clips and the front of the headliner seems to be stuck to the roof of the truck.

 

The trim are held in place with screws and the hard part are the hidden clips
Either by hand or with a small pry tool. Pry the interior trim off with a small amount of force... the clips will eventually release.
My 07 head liner was held up with velcro or also known as hook and loop. along the front over the windshield.