Too remove the rack you first need to remove the plastic top cover. This is preformed by applying outward pressure on the cap. ( toward the side of the car) Once removed you have direct access to the bolts that attach it to the roof of the car.
Once removed, it leaves 4 gaps in the rubber track on the roof. I ordered the caps from the Pontiac dealer for around $8 a piece.
If anyone is interested, I can supply pictures of the rack.