Hi again Peter, where did you purchase the books from? Amazon?
Yes, you can cancel a Kindle book order within seven days through Manage Your Content and Devices. Go to Manage Your Content and Devices (http://www.amazon.com/mycd), click the Actions button for the title you’d like to return, and select Return for Refund. If we refund the item, you will no longer have access to it.
Let me know if this helps.