How do I get rid of outdoor Papyrus plant?

This is a plant I would like to dispose of in my backyard left by the previous owner. I've cut the stalks down to about 3-4" (the plant had grown to about 4'x4'). Is there anything I can put on the remaining plant to kill it or does it all have to be dug up? I just don't like the looks of it at all. Thank you!!!

 

Let it dry out completely. I have killed more than one like that!:(