By default EduX theme will place Main navigation menu in primary menu region.
How To Add or Remove or Disable menu Links
Navigate to:
Home 
Administration Structure Menus Main navigation
example.com/admin/structure/menu
Here you can manage links of main menu.
How to make Drop Down menu
Vani theme has inbuilt feature of Drop Down menu powered by CSS3.
Navigate to:
Home Administration Structure Menus Main navigation
Click Edit button of parent menu link.
Check Show as expanded option of this parent menu link and save.
Customize Main Menu
You can customize main menu from theme settings.
Home Administration Appearance Appearance settings Edu X
example.com/admin/appearance/settings/edux
