How do I remove a restriction in the filler pipe of a 89 cavalier to be able to remove the gas

If you are looking in the filler hole and seeing what looks like a solid piece, it's simply just a metal flap that you should be able to easily push hose past. I don't think Cavaliers ever had anything other than this flap.

Put the rear tires on ramps and try to remove the rubber filler hose off the tank. There is a plastic bucket inside the tank that the fuel pump sits in. It's hard to get a siphon tube to the bottom of the tank.

Pull the hose off the fuel filter and put an auxiliary temporary pump on the line and suck all the fuel out