Hiding menu on mobile

I was wondering if there is a way to hide the responsive menu on mobile and use a menu from a different source. Right now I have two menus showing up on the mobile site. I don’t have a lot of experience using code so if that’s what I need, I’d appreciate it if you could dumb it down :p

My website is lhiagf.org if that helps.

Thank you for any help in advance.