Depending on the year of release of the attachment can vary.
Front bumper
-open the hood.
-under the hood take out the five rivets that attach the upper part.
-wrenched the wheel to the side.
-wheel arches pulled three pistons on each side that attach the fender liner (front part).
-move the wing flaps to the side and Unscrew one nut and one screw on each side holding the bumper corners to the wings.
-take out the five rivets that attach the lower part.
-with the assistant pulls the bumper (look for wires).
-snap together the connectors of the equipment (if any).
Rear bumper
-open the trunk lid.
-in the trunk and remove the rear side trim.
-the side casings (inside the wings) Unscrew the nuts that attach the sides of the bumper.
-Unscrew the nuts that attach the bumper to the back panel (take out the caps in the opening of the trunk).
-Unscrew the screws from the bottom.
-wheel arches take out the rivets that attach the fender liner.
-for wheel arch liners Unscrew the nuts that attach the corners of the bumper to the wings.
-with the assistant gently pulls the bumper (look for wires).
-snap together the connectors for the license plate lighting.
How to remove front and rear bumper Pontiac Bonneville (1992-1999)