If you don't want a product to appear in a search result set at all, you can remove it by hovering over the product and clicking the "Remove" button at the bottom of the product. Please note, the removing of products does not work for category campaigns. The removal of products from a category should be done within your e-commerce platform.
To view a list of products that have been removed from this campaign, go to the Removed tab in the Products toolbox. You can re-add products to the campaign by clicking the blue minus symbol to the right of a product.