To make things clear I’m not writing about deleting an iCloud email account from an iOS device or Mac, but deleting the whole account altogether. Look here for removing an iCloud email account from a device. Read on for how to delete an iCloud email account altogether.
iCloud accounts have often been used as the Apple ID for Apple services like iTunes Store or iOS App Store. Deleting an iCloud account would mean a user couldn’t login and purchased items like movies, TV shows, eBooks and apps wouldn’t be accessible anymore.
Maybe customers losing access to purchased goods is a risk Apple doesn’t want to take, so they disallow deleting an iCloud email account. But there are some options to handle an iCloud email address which may help to circumvent any inconveniences stemming from not being able to delete the account.