Vande

I have put something like this in my userChrome.css:

menu[label="Go"], menu[label="Help"], menu[label="Edit"] {
   display: none !important;
}

because I need screen real estate for bookmarks and see no use for those menus. An exception is the Preferences item in the Edit menu (This applies to the Linux/Unix version). That is why I made the Firefox extension to take the one useful item and move it from Edit to Tools.

Here are some more ideas for your userChrome.css:

#context-blockimage,
#context-copyimg,
#context-copyimg-contents,
#context-openlink,
#context-savepage,
#context-sendimage,
#context-sendlink,
#context-sendpage,
#context-bidi-page-direction-toggle,
#documentDirection-swap { 
    display:none !important; 
}