No drain plug.
If you take the pipe off at the fuel filter the pump only motors for a few seconds then cuts out.
It could take a while to empty the tank like that!
Doesn't take too long to take the plate off the top of the tank,
flip the seat forward,
take the 3 10mm bolts out,
take the pipes off and the fuel pump plug off
put a large plain screwdriver agains one of the ridges and gently tap it round with a hammer. Remember to go anti clockwise!
When you are re-assembling things be careful to get the rubber seal in the right position!