Follow the procedure to delete a repository that is no longer in use. You cannot delete the _control repository.
To delete a repository
Log in to the Repository Manager.
View the log file to ensure that no one is using the repository you want to delete.
In the Navigation View, double-click Repositories. A list of all repositories in this repository server displays.
Right-click a repository name and select Delete....
Verify that the repository name is no longer listed.