Apple's iCloud gives 5GB of free space to every Apple user. You can, of course, add more space through paid storage but in case you're using quite a bit of it, you'll end up with low space.
You can free-up space on iCloud storage and backup by removing data through the iPhone/iPad. This will help you reclaim some free space. Here's how to do it:
Before we dive into it, let's first clear a thing about iCloud.
iCloud stores data as two types:
Storage is the data that's sent from your app to iCloud for sync. For instance, if you sync your photos to iCloud, your Camera sends data to iCloud. So with Contacts, Mail etc. Backup is periodically saved up data that goes into the iCloud backup space. You can access this only when you are restoring your iPhone via a backup. The total storage is the space occupied by both Storage and Backup data.
Now that this is cleared, let's go about freeing up space.
1. Clearing Space from Storage
- Go to Settings
- Now tap on iCloud
- Tap on Storage & Backup
- Now tap on Manage Storage. You should see a list of apps displayed with the space each uses up.
- Tap on an app from the list
- Tap on Edit from top-right
- Tap on the “-” and delete the document data. Should clear a few KB/MB of data out of iCloud storage.
The Documents & Data doesn't remove the app in question. It just removes the documents contained within the app. Note that removing stuff from here will remove the same from all other iOS devices that are connected to this iCloud account.
2. Clearing Space from Backup
Backups occupy a ton of stuff usually, if you have the habit of backing up regularly. While removing backups is definitely not a good option, you do have alternatives like iTunes backup which goes into your system instead of occupying space on your iCloud account.
- Go to Settings → iCloud → Storage & Backup
- Tap on Manage Storage. This shows up the backup data for your iPhone (you might have to tap on the name of your device if you've got more than one associated with the iCloud account).
- Once inside, you can TURN OFF the switch against the apps that you don't want to backup. For instance, if you save your photos in Dropbox or elsewhere, you might want to TURN OFF the Camera app. This will show a prompt. Tap on Turn Off & Delete.
You can turn it back on if you want to.