Click on your workspace's name on the top, right-hand corner.
3
Click "Tools & settings"
4
Click "Workspace settings"
5
On the page it just opened to, scroll to the bottom and click "Delete Workspace"
6
Click the "I understand that all of my workspace’s messages and files will be deleted." field.
7
Click the "Slack Password" field and type your password. After that, click "Yes, delete my workspace" and confirm you action. This will permanently delete your Slack Workspace.