You can now control whether your TidyHQ site will appear in search engines*!
Go to Organisation Settings > Public Facing Page and at the bottom of the options is a checkbox to allow Search Engine Optimisation (SEO).
By enabling SEO, you allow Google and other internet robots to index your site and have it show up in search results.
If you want to tell search engines not to index your site, you should turn this setting off.
* Note: that it is still up to the search engine whether they follow or ignore this directive.
Also, in the case of a site not appearing and your organisation does want it to appear in searches, it may be necessary to help the process along (external link to WikiHow site).