Settings -> iBooks -> Show All Purchases (set to no)
I was able to select the book in the iBooks app then select "move" and at the bottom turn on hide iCloud books.
It has been changed to something even more simple. Go to the app and open it. Once opened go to View and scroll down to "hide icloud books" and you are all done. When you want to access them again, simple go to the same tap and click "show iCloud books".
I don't want to hide I want to free up iCloud space and remove them .
Want to delete books permanently from icloud please
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