A long, long time ago I asked Arthur to put in a way to 'delete' a villager (hey, you can do it with fish!), but, alas, I did not prevail in my quest for that feature. There would have been a lot of creative ways to do it (besides the obvious 'vote them off the island' concept)!

Still, there are dangerous elements on the island, so something unexpected could happen to 'help' you out of your current jam! Otherwise, nature will eventually take its course!