blow hair dryer across deflector, (keep it moving, don't hold it in one place),
and use a thin plastic putty knife to slowly pull deflector off.

Works like a charm

 

heat gun, plastic putty knife.. Then to remove the sticky stuff / glue... I have a 3M eraser wheel, but this brand from grainger is the same thing... This works like magic! Put it on a drill, run it over the glue area, and it is all gone! Very quick, will NOT harm any surface, and no chemicals on the bike at all!
I have removed many badges from cars and door mouldings like this.