How do I prevent suggested training workout from being inadvertently activated during a routine ride

Workouts need to be explicitly selected and started. Don't press the "Ride" button on the workout screen. You can just press the start activity button to start an activity without a workout.

I don't think you can disable the "Training plan" display, but if you have an explicit training plan then this is shown instead of the suggested workouts. You could maybe try to add a workout for tomorrow, and when it's gone you'll always see a "rest day"?

Turn on the Edge ,  tap the profile you want and then Press start .

Thanks, that’s helpful. I realize I can’t deactivate the training plan display.  I must have inadvertently started some scheduled workout, then during a routine ride I had to endure the beeps of 30 minutes of short anaerobic intervals which was frustrating as I could not turn it off mid ride.

Nice & If it happens again , then hit the LAP key , and it Will Go to the next step of the workout and after “x” times the work out is over and you can ride in peace the rest of the ride.

Or just use the menu to abort it. 
Swipe down and use the menu entry

If you can’t find it, look it up in the manual

Allmost , You can abort everything but the Daily sugested training