If you delete a site, your articles are no longer available as a published URL (e.g. end-users cannot see them); however, the articles are still available to Admins on your ScreenSteps account in the All Content > All Articles section.
Navigate to the All Content area
Click on All Sites
Select Delete from the site action menu
ScreenSteps requires you to type DELETE in order to confirm that you want to delete the site. Deleting a site cannot be undone.