Dear Step Mom,
The sooner you stop trying to control his behavior by throwing out his beer, the quicker he'll get to his next "crash and burn" event from his addiction, getting him closer to the day where he finally "gets it" that he cannot use. Throwing out his drug only slows this process. Re read the above responses, focus upon things you can control and avoid his closet. Please find positive, hopeful activities (exercise, community service) to fill your life as much as possible.
Take care