It's up to each member to decide whether or not their photos are available or hidden from public searches.
You can change your default options for new uploads in your account settings.
For content already uploaded to your account, you can update your permissions through the Organizr:
- Hover over You | select Organize.
- Drag the photos you'd like to change into the batch area.
- Click Permissions | Hide/show in public searches.
- Make your selection, then click Change.
Note: Flickr doesn't control the contents of search engine databases. Read more here about how to remove your content from search engine results.