Unpublishing a project site
-  On your GitHub Enterprise Server instance, navigate to the main page of the repository. 
-  If a gh-pagesbranch exists in the repository, delete thegh-pagesbranch. For more information, see "Creating and deleting branches within your repository."
-  If the gh-pagesbranch was your publishing source, your site is now unpublished and you can skip the remaining steps.
-  Under your repository name, click Settings.  
-  In the left sidebar, click Pages.  
-  Under "GitHub Pages", use the Source drop-down menu and select None.  
Unpublishing a user or organization site
- On your GitHub Enterprise Server instance, navigate to the main page of the repository.
- Delete the branch that you're using as a publishing source, or delete the entire repository. For more information, see "Creating and deleting branches within your repository" and "Deleting a repository."