Note: This setting is up to search engines to honour this request.
Login to Shifter Dashboard
Start WordPress and login.
Navigate [Reading] from [Settings] menu
Enable [Discourage search engines from indexing this site] under [Search Engine Visibility Search Engine Visibility] section.
Stop WordPress, generate an artifact then deploy.
Your site is no longer accessible by search engine's crawler.
Never forget to disable [Discourage search engines from indexing this site], then generate and deploy a new artifact by attaching a custom domain name, if you want to allow crawler's access.