There are books in the library that contain information that can be used to do bad things. You can remove any an all cards (for libraries that still use them), or database references to those naughty books. The books will still be in the library, but will be harder to find (even for many librarians).
There are websites that show up in Google searches that can contain copyrighted material for unauthorized download. You can remove those sites from any and all search results. Those sites will still be there, but they will be harder to find.
Am I missing something here? I thought this kind of thing was already happening.