Adding or removing a custom domain for your GitHub Pages site
GitHub Pages is available in public repositories with GitHub Free, and in public and private repositories with GitHub Pro, GitHub Team, GitHub Enterprise Cloud, and GitHub Enterprise Server. For more information, see "GitHub's products."
Before setting up or modifying your custom domain with your DNS provider, you should add or remove the custom domain on GitHub.
For more information, see "Quick start: Setting up a custom domain."
On GitHub, navigate to your GitHub Pages site's repository.
Under your repository name, click Settings.
Under "Custom domain," add or remove your custom domain and click Save. To check if your custom domain is supported, see "About supported custom domains."
If you added a custom domain you can optionally enforce HTTPS for your site. For more information, see "Securing your GitHub Pages site with HTTPS."