How to cancel iCloud on one of my devices?

So my iPhone 4 got stolen about 2 weeks ago. I've tried a lot, but I just can't track it down. I guess I have to face facts. Anyway, I had iCloud on my iPhone, iPad and Mac, but now that the iPhone is gone, I was wondering, is there a way I can cancel iCloud on my phone? Or is there a way I can check if it's been cancelled? I really need help!

Try to see this similar discussion here: https://discussions.apple.com/...0&tstart=0