How can I turn off iCloud storage space warning notifications?
I think your options are limited here.


Turn off iCloud Backup altogether.
Some info on how to selectively or collectively switch off iCloud is here: https://support.apple.com/kb/PH2613?locale=en_GB&amp;viewlocale=en_US
Back up less, e.g. by deciding not to back up your camera roll. I carefully manage what gets backed up and what not (and also which app gets mobile internet access).
To see which apps on your phone are taking up the most space follow these steps:


Open the settings app
Tap iCoud
Scroll down to Storage &amp; Backup and open it
Tap Manage Storage
Select your iPhone

If you're on Windows 10 (unlikely in this forum...), type in the Windows 10 search box Settings and select "Settings Trusted Windows Store App"


Click "System"
Click "Notifications &amp; Actions"
Scroll down to "Show Notifications from these apps"
find "iCloud" and turn it off
This works for other offending app notifications