Purchase a small fuel transfer pump that runs on 12 volts. Push the intake tube into the bottom of the tank and draw out whatever is in the tank until you are drawing clear fuel with no water.
Then replace the fuel filter, drain the water from the fuel housing. Disconnect the fuel line where it comes into the filer housing and suck a gallon of fuel through the line.
Reconnect the fuel line, fill the filter housing with good fuel, then turn the ignition on, but don't start the engine. Wait five minutes and then try to start.
If it starts do not run it for more than 60 seconds, then shut it down, redrain the filter housing, replace the filter, refill the housing with fuel, and try to restart.