Depending on the year of release of attachment is different.
Front bumper
-open the hood.
-wrenched the wheel to the side.
-in the wheel wells, Unscrew the screws holding the fender liner (front part).
-move the wing flaps to the side and Unscrew the nuts that attach the corners of the bumper to the wings.
-Unscrew the screws 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.
-Unscrew the screws that secure the top.
-Unscrew the screws from the bottom.
-in the wheel wells, Unscrew the screws holding the wheel arches and bumper corners to the wings.
-with the assistant gently pulls the bumper (look for wires).
-snap together the connectors of the equipment (if any).
How to remove front and rear bumper Pontiac Bonneville (2000-2005)