There is not currently any way to delete products from the Manage Products block. Once a product is created, it cannot be removed or deleted from the system. This is for compliance reasons, as products created in the system need to be accounted for at any given time.
If you would like to delineate a product as something you no longer wish to use, we suggest changing the product title to something descriptive like Do Not Use.
Learn more about Product Management...
Managing and Editing Your Products
Performing Inventory Cycle Counts