Can you sell branded products as generic?

Here is the situation. Say you have a product that is labeled “Good Stuff” on the box, with the proper UPC code, but the logo and name are not registered or trademarked anywhere. So the brand error comes up when I try to upload it to Amazon. Can I sell it as generic? Even if the box is labelled? Or do you have to ask for a brand authorization? Without proper registry on any database?

Should I just take it out of the original box and use generic boxes to upload it to amazon and ship the product?