Can you cancel an Amazon order that's being prepared for shipping? Well, it depends. The process itself is virtually identical to the one above, but instead of being able to cancel an item immediately you have to place a cancellation request, which may or may not be accepted.
Click Request cancellation.
It's hard to say what exactly determines whether Amazon will accept the request, although it depends mostly on just how close an item is to being dispatched. If it's on the brink of being dispatched, then your request may be declined.
If it's been less than 30 minutes since you ordered an item through a Marketplace seller, you can cancel an order immediately, following the steps outlined in the first section of this article.
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However, if it's been more than 30 minutes since you placed an order, you have to send a cancellation request, following the same process as shown in the section above.