Board Thread:News and Announcements/@comment-34277398-20180414042556/@comment-30323490-20180414161822

He would probably be able to, but considering its size, it would obviously take a) a longer time to chop it off and b) Kakashi would require to put a hell lot more effort than he usually does. This isn't some Kakashi trying to absorb Deidara into Kamui and only be able to take off his hand. We are talking about a bijuu head. And the Gedo Mazo was stationary. Again, Kurama can move, and he could simply swipe Kakashi (and the rest of the land) off with one of his tails.

A good argument would be that Kakashi could try to use Genjutsu on Kurama, but i doubt that he could pull it off with his borrowed sharingan.