If doumentation does not cover your questions or have more to ask / share with other product users or get reply from Official Support then feel free to ask / share on CodeShop Amazon Affiliate plugin Forum.
You can edit Codeshop products usually same way as you do with Wordpress regular posts. To edit Codeshop products You need to use CodeShop menu as CodeShop -> All Products where you will have your all posts with added products so just click on 'edit' link as shown in image below -
you should have almost same interface what you had gone through during adding products using menu CodeShop -> Add New Products, you can know detail on CodeShop add new products documentaion page. In case of Edit products page you will have all boxes what you had during add new products with a new extra display box 'Added Products' below all other boxes where you should see your already added products as shown in sample image below -
In 'Added Products' display box you should have button 'Remove Selected Products' to remove your selected products. You can choose what products you want to keep or remove by selecting products. You should see confirm message after click on 'Remove Selected Products' button to remove your selected products and you need to refresh page to see updated 'Added Products' display box.