It looks like your Main Menu just needs to be docked into Catalog's frame. Have your tried grabbing it with your mouse and place it in the area above your Standard tools?
I cannot grab the menu bar. That is why it's frustrating.
Have you tried going into Customize mode in Catalog?

This should allow you move any menu items around.
I’ve included a screen capture of my customize menu. I cannot remove the Main menu from the toolbar. Also if I hit reset, it asks if I want to do anything, but nothing happens. I have rebooted my computer several times thinking that may reset the program, but that doesn’t help either.
Try this
WARNING - You'll lose any Catalog configurations and it'll reset to the default view of Catalog.