If you are talking about the 3 piece chrome stainless pieces that are on the sides and top, they ride and clip over plastic clips. The plastic clip has a screw for mounting. The stainless piece needs to be pryed slightly at each edge to remove if you are going to replace/ save. If that's not an issue, it can come off very easy!
Those moldings are held on with plastic clips that have a slot where a pin or rivet holds the clip to the body. To remove those moldings just push the molding in the direction away from the car or to the outside. You only have to move the molding about a 1/8" or so to release them.