iBooks 3 introduces a new Purchased Books feature that gathers all of a user’s iBooks that have been purchased from the iBookstore into a single collection for quick and easy access, allowing books not already on the device to be easily downloaded from iCloud at the tap of a finger.
For users who may not want to see some or all of their purchases right in the iBooks app, however, the good news is that you can either turn this feature off entirely, or selectively hide individually purchased items from the Purchased Books collection.
To disable the collection entirely, simply go into the iBooks section in your iOS Settings app and toggle off the option to Show All Purchases; the Purchased Books collection will disappear entirely, although you can still download your purchases via the iBookstore as you could in prior versions of iBooks.
On the other hand, if you simply want to hide one or more specific items from your previous purchases, you can go into your iTunes Store account, using iTunes on your computer, and hide it from the Purchased section in there.