How to Hide Menu on Mobile Version

If you look on your mobile phone the default menu is listed, stacked vertically and it just looks like an eyesore. I installed a “responsive menu” to get the hamburger menu onto the mobile version but now I have both the ugly stacked vertical menu and the responsive hamburger menu. How do i hide the default menu and just keep the responsive one?

I’ve tried many different CSS codes from searching the forums, none of which seemed to work.

The page I need help with: [log in to see the link]