What about the keyboard command for Clear Recent History?
{Ctrl + Shft = D}

If your boss has some type of rule that browsing history shouldn't be cleared so he can follow his employees around, he's a damn fool if he is relying upon using browsing history to track the websites that employees visit while using company equipment and/or on company time. Browsers have a Private Browsing (Incognito) feature that doesn't save any browsing history.

A local area network server firewall (if your company runs its' own intranet) is a lot smarter way of tracking everything that is going on in the office, and there's no way an employee can erase his/her tracks from the server.

Thank you for the quick respond, the-edmeister.

Our boss is not smart enough to understand it is a fact. But the main question is, how to completely wipe out that options button ? This issue is emergrncy.

The Menu Editor extension - https://addons.mozilla.org/en-US/firefox/addon/menu-editor/ - provides a feature that allows the user to hide (un-check the visible box in the right column of the Edit Menu box in the interface with Tools selected) specific meru items.

There are a lot of ways to clear such personal data, either via Clear Recent History or directly by deleting the History in the Library or sidebar even if Private Browsing mode isn't used to prevent saving this data in the first place.

If you want to see which sites have been visited then you should look at others means outside Firefox like a router or firewall with a password protected logging feature that can't be bypassed or a program like Wireshark to log internet access.

Thank you, sir. This is legit.