How can I delete a draft text message from my Sony Xperia Z1???

[AC Question]

I have two draft messages in two individual contacts that I just cannot delete.
So when I want to send a new message to either of these two contacts, the earlier draft messages are always there. I have to backspace to delete the draft message, and compose a new one to send. But next time I need to compose another message to the same contact, the old draft is there again.
I don't want to delete all conversations\message within this contact, just the annoying draft message......