How do you remove the gas filler tube ?

Hopefully the gas is below the rubber seal in the tank. If it is, nothing can spill.
Take the 3 screws out.
Leave the seal in the tank.
Spray some WD-40 around the seal and tube.
Push the tube into the tank a couple inches (this gets the seal and tube lubbed).
Start pulling it out, but as your doing it, spin the tube so the end faces the upper corner of the trunk.
Pull it out.
Done

To install reverse the order. WD-40 is the key.