Hide secondary menu items from Divi mobile dropdown menu
The Secondary Menu items are being added to Divi mobile menu by default to the bottom of the menu (below the main menu items).
To remove the secondary menu items from the mobile menu go to Divi -> Theme Customizer -> Mobile Menu Customizer -> Menu Settings and find the SECONDARY MENU ITEMS POSITION setting and select the Remove secondary menu items option.
You can also move the secondary menu items above the main menu items if you need so.
This feature is available for the Default, Centered and Centered Inline Logo header formats.