If let's suppose our product is not according or related to a customer so how can we sell our product to that customer?

Thanks for the question, Using an Italian approach of marketing and sale, it clearly stipulates that if demand becomes inelastic then create factors that can make it elastic.

Therefore this is when you are supposed to use marketing gimmicks by convincing the client, of the advantages of the product for-example pricing could be a determinant in this case and as well using a related trick of comparing it to its other product like that serves the same purpose hence changing his her mind.

You have Grammar mistake, you should ask (( how can we sell a product to a customer who is not interested in the product)).

The answer is " You should try to convince him with our product and mention the benefits of using this product "