Pontiac 1996 Grand Prix Owner's Manual page 23

To unlatch the belt, just push the button on the buckle.
The belt should go back out of the way.
Before you close the door, be sure the belt is out of the
way. If you slam the door on it, you can damage both the
belt and your vehicle.
Driver Position (4-DOOr Models)
This part describes the driver's restraint system. If you
have a two-door model,
see "Drives Position (2-Door
Models)" earlier in this section.
Lap-Shoulder Belt (4-Door Models)
The driver has a lap-shoulder belt. Here's how to wear
it properly.
I. Close and lock the door.
2. Adjust the seat (to see how, see "Seats" in the Index)
so you can sit up straight.