If you frequently back up multiple devices to iCloud or have a lot of videos and photos, you may easily have problems creating new backups since you won't have enough available space.
By following the guide below you can free up space by deleting data from applications that you do not use or that you have not yet deleted from your device.
Go to Settings on your iPhone or iPad.
Tap iCloud.
Tap Storage & Backup.
Tap Manage Storage.
In Documents & Data, select the app data you want to delete
Tap Edit at the top
Tap the Delete button to the left of the folder you want to delete
Tap the Delete button on the left that will appear
Confirm deletion
Alternatively, if you want to delete all data for a specific app, go to the bottom and tap Delete All
Confirm deletion
Source: planet-greece.blogspot.com
