A Slack slash command, /clean, that deletes your own messages in bulk, by channel, age, keyword or attachment type. Deleted messages cannot be recovered.
After a workspace adds the app, each person runs /clean login once, then /clean help. /clean on its own is a dry run (a preview that deletes nothing). Add delete to really delete.
Per workspace, the app's bot token. Per person who runs /clean login, their Slack user token, encrypted. No message content is stored or logged. The token is used only to list and delete that person's own messages when they run the command.
Run /clean logout to revoke and delete your token. Removing the app from the workspace deletes everything stored for it.