CacheFire is free to use tool which lets you specify some urls or websites from firefox browsing history, you can either specify the complete url of any we page you want to remove from firefox history or partial keyword which matches in the URL. It will not only remove the URL or website if you had visited or even if you visit after installing this tool, it will remove the website from browsing history in real time.
For Example – To have pages removed from the history if their web address contains the word "games", simply enter "games" (without quotes) in the input box and click Add.
If Firefox is running during installation it must be restarted before CacheFire will function. After the application GUI has started, enter a string; say www.example.com and click Add. Switch to Firefox and press Ctrl+H to bring up the history panel.
Now browse to www.example.com. You should see the history item for www.example.com first being added to the browsing history and a moment later removed by CacheFire