Put them in a big can or watertight container of any kind, put in the papers, and fill with water, and let it sit for awhile, perhaps overnight. I use one of those garden weasel tillers to stir it up. The ink runs, and it becomes a big runny mess, that will try into a glob that is unreadable. It works best if the paper isn't tightly stacked, since the water won't really get to it and it's tough to separate. Takes a little experimenting to get it right and I've only done it once, awhile ago, so I don't recall exactly what I did.
My other option is to use it for starting grill fires with my chimney starter. But that doesn't take much paper, so it's not a solution for a big purge.