There is much you can do. CEE laws include the "right to be forgotten". That means, you have to personaly find each and every site and search engine that could have a track of the information you want to remove, an ask the site manager to remove it.
No problem for major search engine like google, at least at first sight. You ask them to de-reference the original link and they to it. They are glad of it because it says: if it exists on Internet it is referenced by Google, and if it is no longer in Google it has vanished. The reality is much worse. If another site has a link to the original page, or has partial copies - allowed in copyright laws of many countries, that indirect link will remain. Neither Google nor anyone else is asked to carefully clean the information. Only you are responsable to find every link or site.
Following is just a personal opinion. Google and other major search engine are particularly glad of that, because it re-inforce their position without forcing them to be responsable of anything else than their own database.
So as long as indirect links are not concerned by the right to be forgotten, the only thing than a sane human being should do is to never post an information that could later be harmful, because once published, you have no control on it. Even if you post it on a said private zone - not speaking of corporate private networks- you should think twice of that sentence shared by military intelligence services and anarchists: a secret shared by more than two persons is no longer a secret.