To hide items on the Navigation Menu, click into Admin and then go to Templates to view and edit the Navigation Bar.
From here, click on the menu item you would like to hide from the Navigation Bar, so that the 'Update Menu' pop-up appears. Uncheck the "Visible" option and click Save.
Once this has been completed the menu item will no longer appear.
*Note that while a menu item may not display on the Navigation Menu, it may still be accessible to users through other links if they have permissions on that module. If you would not like a user group to be able to access a module menu item at all, you will need to update Group permission rules and settings. For more information about Group Rules and Permissions, please click here.