You can tell Google not to index your website using <meta> tags. Add these in your Settings > Site details > Additional <meta> tags:
<meta name="robots" content="noindex"> <meta name="googlebot" content="noindex">
To completely block anyone, including Google, from accessing your site’s contents you could add Password Protection via your Settings > Site Details > Site Password.
Removing content from Google’s index can be done only when you use a personal domain for your Cargo site, and by using Google’s Webmaster Tools. Once you have signed up, follow this guide on removing content and pages. (They will need to know where your ‘sitemap’ is located, which in your case is here: http://your-domain.com/sitemap.xml.)