Multi-website management is only available in the Enterprise edition.
This topic is part of Frontend Menus where you can learn more about all available types of frontend menus, how to configure them on other levels, and edit their items.
To customize one of the storefront menus (e.g., commerce_main_menu) or customer/partner portal menus (e.g., customer_usermenu) for a particular website:
Navigate to System > Websites in the main menu.
Click on the website you would like to edit the menu for.
Click Edit Frontend Menu.
Update the menu contents following the guidelines provided in the Edit a Frontend Menu section. The changes apply automatically.