Yes, you can use BackHub to archive your GitHub repositories. Once a backup is complete, you can delete the original repository in GitHub. Since the upstream for creating further backups from the original repository will no longer be available, the backup is being archived automatically and listed in a separate section in the bottom of the page. You can restore the repository back to GitHub from an archived backup anytime.
Please note that not all data can be restored to GitHub directly and might come in a different format. You can learn more about what you can restore here.