How can I disconnect an iPad from my iCloud account?

Hello,

I sold my iPad (New iPad or iPad 3? it's the model that came out before the current model) after resetting it as factory setting. But I keep seeing the iPad on find my device and it seems like it's getting my photos from my iPhone and Macbook Pro. Also, I see the person's caldendar events are synched to my Macbook calendar and I also sometimes see the person's pictures on my photostream. I asked the person to delete my iCloud account and told her to use her own; however, the iPad is still synched with all of my apple devices. Is there any way that I can completely disconnect/delete that device from my account?

Thanks a lot in advance.