Can you pick the tank up ?
If so, tighten your cap and breather.
Lift the tank and stand it upside down on something ( workmate bench )
with the breather at the lowest point.
Leave to stand ( an hour or so ).
Place container under breather and loosen breather.
The water should be at the lowest point, so when water stops, and fuel starts to flow - - you should have cleared the worst of it.
Otherwise, use a long syphon and suck from the lowest point in the tank.
Jim