It could be a case that you don’t want some sites which you browse from your office or home computer to show up in recently types URLs history in FireFox address bar.
All those firefox history cleaners does not allow you to do delete a specific URLs from the address bar history in firefox, so if you want to clean a particular URLs typed before in the recently typed URLs list of firefox address bar you would need to delete it manually.
In order to delete a single entry in the firefox address history, open FireFox and type some initial characters of the URL you want to delete and then it will appear move your mouse over but don’t click and press shift+delete to delete it from the address bar history.