You can't. It's not allowed in most places for good reason.
You could return it where you purchased it. Store credit if you don’t have the receipt
@flamingomom, oh no the one he currently drinks I do .. the doctor prescribed this but it didn’t agree with him
You could donate it to a food shelf to help a family in need.
If you sell it on the marketplace on Facebook,eBay or anything like that they require proof it was purchased.