ibooks sort books by size

My ipad is getting full. One way of making room would be removing a few books from ibooks. Using itunes, I can see how much space each book takes, but I can't seem to sort the books by size. Is this possible at all?

Then, is there a way to delete books via itunes, or do I have to do this on the ipad?

Details:

ipad2

iOS 8.2

itunes runs on Windows 7

I don't know my version of itunes