Here was where I got the information (different forum site). I think they may have meant if it is deleted from the "purchased" page and not the "I'm reading" page which is what the customer question referred to. So, thank you for making me double check.
"Should you delete a purchased item, you have 30 days from the date of deleting to remove it from the Trash. After 30 days have expired, you will no longer have access to the content, and will have to re-purchase it to read it again.
All deleted items remain in your Trash for 30 days. To undelete an item, check the box next to any title and click the orange Undelete button—your content will be moved back into your Library. To permanently remove items from Trash, check the box and hit Delete Forever.
7 hours ago · Report"