Hello,
1.
Choose the proper header type (your current) http://prntscr.com/iyd333
Switch the mobile view of your header http://prntscr.com/iyd3v3 Find the Mobile menu element, you will find the option to enable/disable the category menu and drop-down to chose which one to show. This menu is created in the Appearance > Menu.
2.
Please deactivate all the plugins not related to the theme and switch the parent theme, provide your site admin access as well as FTP to the private area.
Best Regards