Maybe if you ask to the driver properly he could stop the engine, and consecutively all the consist too. Just kidding
From what i know if you want to "Simple drive"(Start/Stop the running, and NOT the engine) you have something known as "Commands" that appear "clicking with the RMB and pressing CTRL onto an engine/car, so then you can give him the order of "Drive"(Train starts moving, without exceeding speed limit and signals, something lookalike an "Autopilot" mode), "Drive to"(same as before , but this time, driver goes to a selected place i.e. Container station, or woodmill and starts a procces "Load/Unload,......") and "Drive to Trackmark" (This time drives to a placed object in the track and doesnt have any function)
But if you are talking to Start/Stop the engine, there is no option more than the SD70s of Phil C's that are built-in
Greetings and good luck