Squire Fat Strat pickguard plastic adhesive removal help?

My son just got a Squire Fat Strat HSS, Montego Black Metallic. A bunch of plastic started peeling off the pickguard, so we just peeled it all the way off. Now there are dull sticky patches of what appears to be remaining adhesive on some of the pickguard surface. What is a safe, careful way of getting this leftover adhesive off?