Apple provides each iCloud user with 5GB of free storage for iOS device backups, application documents and data, and iCloud e-mail, but if you have multiple iOS devices, or keep a lot of photos and videos in your camera roll, this can quickly fill up. Further, if you’ve recently upgraded to a new iOS device, the backup from your old device may still be laying around in your iCloud account, taking up additional space. Fortunately, it’s pretty easy to see what’s taking up space in there and clear it out. Simply go into your iOS Settings app, select iCloud and then Storage & Backup, and then Manage Storage. This will show you first a list of all of the backups stored in your iCloud account for each of your devices, along with the device name, followed by a list of apps storing data in iCloud. You can tap on any of these items to see more information; backups provide a button to delete the entire backup, while application data will provide a list of items that can be deleted individually by using a swipe gesture or tapping the “Edit” button in the top-right corner.
If you’re a Mac user with OS X Lion or Mountain Lion, you can also access this information from your OS X System Preferences by going to iCloud, and clicking the “Manage Storage” button. Note that some iCloud data such as Photo Streams, Calendars, Contacts, Reminders is not included in the 5GB of user-accessible storage—it doesn’t count against your limit, nor is there any way to delete it. Apple also keeps up to three iCloud backups for each of your devices, but only the most recent backup consumes your iCloud storage; deleting the current backup will also delete the previous versions.
Lastly, if you’re using multiple iOS devices in a family, it may be worthwhile to consider switching each user to their own iCloud account—that way they each get their own 5GB of storage, saving you from the possibility of having to purchase additional storage just backup all of the family devices.