Disable Mobile

I have GPP 1.7.8 installed. I am also using QuadMenu Pro 1.7.3. I have QuadMenu set to replace the primary GPP navigation via its integration menu option so that I can use the mega menu features. This part works fine. The problem is on mobile. Both GPP and QuadMenu menus are showing on mobile. I want to disable the GPP menu completely. How do I do this? Tom's disable plugin -- which your help document says to use -- does not work (and hasn't been updated in 4 years).