How to Delete all the stored files and data of snapchat through my iphone 5s. Ios8?

I tried searching the web but was not able to get the solution to it. My friend sent me some pics through snapchat which i took the screenshot off but later deleted them. It is still somewhere store in my iphone. I deleted the app but still i have those pics store somewhere in my phone. I came to know this when I tried sharing a pic on instagram and I was able to check all these pics i deleted earlier.

It went into your iCloud. Go to setting go to photos then iCloud and log into iCloud and delete the pics. Then done.