Removing Panel Adhesive

Having suffered a number of numberplate thefts a few years ago (despite plates being fitted with antitheft screws. I have taken in recent times
to sticking plate on with panel adhesive and never had a problem.
About 12 months ago Billy scrote and his mates tried to pry off my front plate leaving pry marks on the bumper and cracks in the plate.
Initially the cracks were trivial and didnt bother me, however they have started letting in water and the plate is slowly delaminating.
I plan on removing the plate with a "cheese wire". However this will leave a good amount of adhesive on the plastic bumper.
Can anyone recoment a decent way of getting the worst of it off? Im planning on a wire wheel in the grinder, but am open to different or better ideas!
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