To delete all products in one portal using SQL do the following: 

In DNN SQL console run the following but make sure to replace @PortalID with correct #

DELETE FROM
   {databaseOwner}{objectQualifier}Smith_Products
WHERE
   [PortalID] = @PortalID
 
You can get the Portal ID by:

SELECT * FROM {databaseOwner}{objectQualifier}PortalAlias

To delete all your images replace "Smith_Products" with Smith_ProductImages.