There are three ways to kill an engine that is accepted practice.
The first is to close the throttle until the engine stops.
The second is to have an additional servo to close the choke cutting off the air to the engine.
The third is to kill the ignition by either grounding out the coil (magneto) or removing the ignition voltage. (the EDI switch you mentioned)

All are accepted practice. I personally use the choke feature to kill my engine.