1. Click on the All Categories under your store name (left hand side) 2 . Find the category you want to delete and click though
3. Make sure it's empty of any products before you decide to delete
4. Just next to where the thumbnail goes there's an option to edit/delete
5 - Press delete and wait for a week for it to fully delete from your store front.
Personally, I would just remove any thumbnail and set the category to hidden and rename it (i.e zpare cat) so it will there when you want a new category then rename/add a thumbnail and unhide when the time is right
