You can change a repository's visibility from public to private if you're an organization owner or have admin permissions for the repository.

Warning: When a public repository is made private, public forks of the public repository are detached and put into a new network. They are not made private. For more information, see "What happens to forks when a repository is deleted or changes visibility?"

  1. On GitHub Enterprise, navigate to the main page of the repository.

  2. Under your repository name, click Settings. Repository settings button

  3. Click Make private. Make Private button

  4. Read the warnings. Warnings popup
  5. Type the name of the repository that you want to make private.
  6. Click I understand, make this repository private. Warning Popup