You can delete a workspace by going to Settings>Users and Workspaces, choosing the workspace and then choosing General.
There you can delete the workspace.
Make sure you definitely want to do this!
What happens when you delete a Workspace?
All rating categories, comments, highlighted statuses on tickets, internal tags, filters are deleted. Connected users are also disconnected
Reviews left in this Workspace are deleted
Admins and Account Managers not connected to other Workspaces will still be able to use your account
Agents not connected to other Workspaces will not be able to use Klaus and will see a message asking them to contact their admin