We never store any of your Slack data on our servers, everything is served in realtime to your CloudShow client. If you would like to remove your Slack authorization token you can do this from the Slack website, or you can click the 'Deauthorize' button in the Slack app settings in your content frame. If you're unable to access either of these feel free to contact us and we can remove your Slack token from the CloudShow server on your behalf.