How can I remove an empty main menu category in Ubuntu Budgie 19.04?

Solution 1:

You are not alone in finding Menulibre an unsatisfactory (albeit official) solution Issue 789 Issue 939. You may wish to add your voice to those assembled multitudes to encourage a satisfactory solution. Until then, have you tried Appeditor (more)? That requires:

sudo apt install flatpak  
sudo flatpak remote-add --if-not-exists flathub  https://flathub.org/repo/flathub.flatpakrepo
sudo flatpak install flathub com.github.donadigo.appeditor