2019 note: The whole premise of this program may be obsolete based on a change announced by Slack at https://api.slack.com/changelog/2019-03-wild-west-for-files-no-more. Think carefully about whether blowing up your security model is the correct approach.
This simple little program breaks about a million basic security rules to delete outdated files from your Slack domain.
More warnings, and information on how to set this up, are available in creds.py.
This is largely taken from https://gist.github.com/thesoftwarejedi/d78af9ee12b7f7a9d3e7
The bulk of the credit goes to @thesoftwarejedi.