I now have unlimited iCloud on my sprint protection plan so I no longer need to pay for iCloud. How do I discontinue

Follow the instructions in here.

Downgrade your iCloud storage - Apple Support

Note that Sprint's cloud service and Apple's iCloud are 2 different things. Only Apple's cloud based storage and sync service is called iCloud. Everything else is just cloud based storage and is not nor is it related to Apple's iCloud.

Any data on your iCloud account that exceeds the free 5GB space, will deleted when you cancel your iCloud storage plan.

You will need to download it form iCloud, and upload it to Sprint's cloud service manually, as there is no direct connection between the 2 services.