memory is full

I have an iPad 2 and have recently signed up to use the iCloud. But now I keep getting messages from the iCloud telling me that the memory is maxed out. As far as I know, I only use it for photostreaming which I thought didn't count towards the minutes. I even went through the settings and made sure the iCloud was off for all the apps except iPhoto and iCalendar. What do I do inorder to clear the memory on my iCloud so I stop getting that memory maxed out message?