You can add and/or remove category items from your navigation menu by doing the following:
Login to your website admin.
Click on the Navigation Menu icon.
Click View/Manage Categories.
Uncheck the category you would like to disble, or Check the category you would like to enable on the website.
If you need to create a new category, click on Add New Category.
You can also set the order of the categories from this list as well.
Note: Category items cannot be positioned (ordered) above Main Menu items.