Currently, there is not an "Administrator" option for Staff, however, you can add them to your Staff and mark them as "Offline". This will prevent them from displaying on your Listing as a Service Provider. To learn more about adding a Staff member, follow the steps laid out in the Adding Staff section of our Help Center.
Once you've added the Staff member, you can assign the level of permissions that you would like this individual to have access to. Please note that all permissions are assigned by default when you add the Staff Member. This collection of tutorials will walk you through the various permissions that you can assign to Staff.