In order to delete a category, you have to go to the Product catalog menu - Categories management and click on the "More options" button located near each category. This button allows you to delete the respective category.
Attention: If you delete a main category, you can move all its subcategories under another category or you can turn them into main categories.
In case it does not have subcategories, but does contain products, you can choose to delete those products or to move them under another category or subcategory.
Listed in: Categories settings