There are two different sets of demo products.
Apparel, T-shirts, toys, etc
These are the products of our demo store. If you see them, it means that you haven't assign your Ecwid store module to the correct Store ID. Please do it and you will be able to add your own products. How to find your Store Id: How to get your Store ID
Fruit and vegetables
These are the demo products that are added to any newly created Ecwid store. You will also see some test orders and customers. We add them for you to play with products/orders right after the account creation.
Feel free to remove them.