Cancel an Accidental Purchase
You are able to return a Prime Video order if you haven't attempted to watch or download it.
You have 14 days to return an accidental or unwanted Prime Video purchase in the EU; and 48 hours in the rest of the world:
From the Prime Video app or PrimeVideo.com website, select My Stuff, then Purchases & Rentals.
Select the title that has been purchased or rented in error. This will load the title’s detail page.
When the page loads, do not click on the play button.
If your order is eligible for a refund, you will see and be able to select a button marked Cancel Your Order.
Choose a reason for the cancellation from the drop-down menu, and then click Cancel Order. After the cancellation is complete, your refund is issued to the payment method used for the order.
The video is also removed from My Stuff or Purchases & Rentals as a part of the refund process.