Buyer here, trying to return a beauty product

I bought cologne on Amazon and the ratings were great. However, after reading the comments, many of them said it was a well-made knockoff. This made me want to return it and I haven’t even opened the box or anything.

Amazon’s policy doesn’t allow us to return such items, but after reaching out to the seller, they said: “Send us back the item we will refund you”. I don’t know how to send it back securely because my Amazon app isn’t showing a return button or any changes. Do I just return to sender and hope for the best?