How do delete permanently (not hide) some of my iBooks?

I have several iBooks that I have no interest in reading again. I want to delete them completely, but have only been successful in hiding them. I don't even want them in my iCloud storage now, but can't figure out what to do. I have iOS 9 and probably hundreds of books.

Solution 1:

Open iBooks and right-click on a book you want to delete. When you right click you get several options and bottom option is delete. It then asks you if you want to permanently book and it deletes it from iCloud as well.

Solution 2:

As of iOS 11 & OS X 10.13 (High Sierra), there is no way to permanently delete items from iBooks. The closest option is to hide them, where they can only be restored (unhidden) from iBooks on OS X.