Bulk delete Slack attachments
› slack-cleaner --token [token] --file --user "*" --before 20171101
Will delete file -> Welcome to Slack!
Will delete file -> Channels Keep Your Conversations Organized
Will delete file -> Uploading Your Files Into Slack
Will delete file -> Getting Started with Posts
491 file(s) will be cleaned.
Now you can re-run this program with `--perform` to actually perform the task.