Slack is a cloud-based set of proprietary team collaboration tools and services.

That sounds crazy but you might need it.

Here I show how you can delete data from the channels.

Create an access token.

Install slack-cleaner utility.

Install dependencies

sudo apt-get install python-setuptools
sudo pip install -U setuptools

Now run:

slack-cleaner --token xoxp-23189103525-13189103541-328208874179-f0c13305132c197ca1b6ec0044befdff --message --channel general --user "*"

If all fine run it for real using the --perform switch:

slack-cleaner --token xoxp-23189103525-13189103541-328208874179-f0c13305132c197ca1b6ec0044befdff --message --channel general --user "*" --perform