Navigate to Confluence administration → Space Privacy → Dashboard → Extranet spaces.
Extranet spaces overview
Find extranet stats with the new Space Privacy dashboard.
The dashboard will display all extranet spaces in your system. At the top of the list, you will see a summary / an extranet space count, and the list itself contains all extranet spaces listed as entries, including their keys and user count.
Use the gearbutton to navigate to the extranet configuration.
Use the back-tick button to convert an extranet space to a normal space.
You can also use the search field to find the right space faster.