Maybe you posted the wrong files or maybe the files have been revised and you want to remove the previous version of the files and before you post the new version and the files have not expired off Info Exchange.  In any case, you can make the files expire prior to their expiration date by simply going to the Info Exchange Activity Center. Then, go to the Outbox and select the files that need to expire and in the Task select Modify Info Exchange settings.  Select Remove Content from Info Exchange Server and the files will expire immediately.