The Recent Tags smart folder and the separator below it are normal bookmarks, so right-click -> Delete (you may have to remove the separator in the Library).

#menu_tabsSidebar,
#bookmarksToolbarSeparator,
#bookmarksToolbarFolderMenu,
#menu_unsortedBookmarks {display:none!important;}

#appMenu-library-remotetabs-button,
#appMenu-customize-button,
#appMenu-more-button {display:none!important;}

#context-bookmarkpage,
#context-sep-sendpagetodevice,
#context-sendpagetodevice,
#inspect-separator,
#context-inspect {display:none!important;}

Thanks for the great tips :) Is it possible to hide the top level menu of main application menu bar? I wanna completely hide History and Bookmarks menus :) Is there a code for that too? Thanks :)

Use these selectors:

#history-menu, #bookmarksMenu

thanks very much :) Is it possible to add Clear Recent History to Tools Menu now that History menu is hidden ? Also if you don't mind can u plz also help me with some more context menus?

It is not possible to add items to menu. You will have to use the History item in a Library drop-down list or add the History button to a toolbar or overflow area.

/* hide context menu items */
#context-searchselect, #context-keywordfield,
#context-sendimage, #context-sendaudio, #context-sendvideo,
#context-setDesktopBackground {display:none!important}

Thanks buddy :) However, Email Image and Search Google for... do not work! Which ones are for these?

I think these should work.

You can look for the text labels in browser.dtd and then check browser-context.inc to see to what #context item they map.

• https://dxr.mozilla.org/mozilla-release/source/browser/locales/en-US/chrome/browser/browser.dtd
• https://dxr.mozilla.org/mozilla-release/source/browser/base/content/browser-context.inc

Thanks, very helpful, however I didn't find name of 2 menu separators inside, where can I find them? Thanks :)