Why can't I delete books I purchased in IBooks? Even if I delete them from my devices they remain in iCloud forever.
Why does Apple not allow to delete? Like in Kindle?
Apple - incurable control freaks.
Easy solution: Don't by from Apple, buy from AMAZON.
As far as I know Apple have not said why (these are user-to-user forums). If you want to leave feedback about it : http://www.apple.com/feedback
You can hide them from the cloud so that they don't show for redownloading : iTunes Store: Hiding and unhiding purchases - Apple Support
(If using a Mac with Mavericks or Yosemite on it hiding is done via its iBooks app in a similar way as above.)
delete iBook purchases from iCloud
