If you’ve wanted to prevent your site from appearing on Google Shopping or Google Advisor, you now have a chance to do so within Webmaster tools. Webmasters can now opt out of having content that Google has crawled from their site displayed on:
To do so simply visit the Opt-Out page and you will be presented with the following option.
Simply click the big red button to exclude your site from showing up in the Google properties. After choosing this option, content crawled and sourced from your site via Googlebot will not be displayed on any of the properties listed above. Content currently being displayed on any of these properties will be removed within 30 days of opting out.
Note that opt-out is only available for domain level sites and currently applies only to services hosted on google.com and won’t apply to other Google domains.