Looks like this would do the job, but it costs £105 UK:
http://www.litera.com/products/metadact.html$19 sounds a bit better, but sometimes you get what you pay for:
http://www.digitalconfidence.com/BatchPurifier.htmlThere are quite a lot of free, trial, and retail offerings that batch process folders or drives. Search google for something like "batch metatada removal redaction microsoft office pdf"