I don't believe they have a drain plug as such. Loosen the fuel line and pull it off , the fuel will drain then. Acually it is best to loosen the clamp on the at the other end from the tank. Should be a short line between the tank and the hard line. Then you car direct the fuel into the big bucket you have sitting there ready.
When the fuel is drained the rest of the line comes off and the screen unscews from the tank.
As a note, most have found with the tank reading E, you may have more than 5 gals left in there. So be ready with enough containers so that you don't drown under the car.