Eric - Please note that Purge will not purge all iterations of all revisions of your files. At most it will purge everything but the last iteration of the latest revision. Also, Purge purges the data in chunks. Therefore, you may run into ReferentialIntegrityViolations if you are trying to purge everything at once, but the related files of the files included in a particular chunk are not included in that chunk. Chunk size is controlled by a preference in Preference Management (-1 is unlimited, but not recommended as it can lead to OutOfMemoryErrors):
If you set chunk size to 1 then that will at least let you purge all of the objects that don't have ReferentialIntegrityViolations, but it might take a while depending on how much data you have.
The Delete action allows you to delete all iterations of a selected version:
Can you generate a search that will return all data and then select everything for Delete?
If that doesn't work it may take a combination of purging and deleting.