Is there any way to hide or remove Firefox 22 title bar in OS X 10.8.4?
Short answer: no
It has been a bug since firefox 13 Even though autohide is set to 'true' the toolbars won't hide in fullscreen.
Best option is to go to view -> Toolbars and uncheck the toolbars in the top menu But this leaves the 'tab toolbar'
So if you really want to hide the toolbars you should open the page in a different browser.