When you view a product in the Product Properties page, you can delete it by pressing the "Delete" button at the bottom of the page. See the preceding topic called How To... View All The Details About One Product.
You'll want to heed the warning that MakeLifeEasy presents to you:
when you delete a product, you permanently delete all assets based on that product.
Usually you'd only delete a product when you entered it by mistake and/or it's not used by any asset.