iCloud: Remove an iOS device backup from iCloud
You can free up iCloud storage space by deleting the entire iCloud backup for an iOS device, such as a device you no longer own. If you’re restoring a device from an iCloud backup, you must wait until the restore operation is finished before you can delete the backup.
WARNING: If you delete the iCloud backup for your iOS device, iCloud stops automatically backing up the device.
Instead of backing up your iOS device to iCloud, you can back up your device using iTunes. For information, see the iTunes Help topic Back up your iPod touch, iPhone, or iPad.
Remove a backup using your iOS device
Do either of the following:
On iOS 11: Go to Settings > [your name] > iCloud > Manage Storage, then tap Backup.
On iOS 10 or earlier: Go to Settings > [your name] > iCloud > Storage (or Settings > iCloud > Storage), then tap Manage Storage.
Tap the name of a device whose backup you don’t need, then tap Delete Backup.
Remove a backup using your Mac
Choose Apple menu > System Preferences, click iCloud, then click Manage.
Click Backups on the left, select an iOS device on the right whose backup you don’t need, then click Delete.
If you don’t see Backups on the left, your iOS devices don’t have iCloud backups. For more information, see Back up your iOS device to iCloud.