Half water half bleach in a mug, placed in the microwave for 30 secs or so. Don't zap it too long or else it'll catch fire, literally happened to me.
Or you could clean it out with a tad bit of water if it's really full of resin, put that water on a plate and then microwave it for a good 30secs -1min and you'll be left with a powder you can do whatever with. It'll get you high but it's not the best.