I assume this is diesel? Not sure what it's problem is but just to get it shut off you can try closing the valve on the fuel filter, assuming it has one. This might leave you with some air in the line and if so, you would have to bleed it out before cranking again. If nothing else, close off the air intake with a heavy rag or piece of cloth to choke off the air supply.
Don't know how that engine works, but most likely you simply pull back the throttle all the way and it *should* cut off, just like with the JD 750 I used to have. I believe that it was shutting off the diesel fuel coming out of the injector pump.
With the JD 790 I have now, it has an electric solenoid valve that deenergizes and closes off the diesel fuel, when you turn the ignition key off.