In this quick tip we will see how to deactivate global Menu in Unity.
To deactivate Global Menu for applications, open terminal and enter the following command:
sudo apt-get remove appmenu-gtk3 appmenu-gtk appmenu-qt
To deactivate golbal Menu for Firefox and Thunderbird enter the following:
sudo apt-get remove firefox-globalmenu thunderbird-globalmenu
I tested both commands above and worked fine.
Global Menu activated
Global Menu deactivated