In a kingdom? Yes, but would be extremely difficult since there's usually a ton of people. If you kill the last surviving member of a clan, that clan will be destroyed (just tested it on a vanilla Sandbox game). Trouble is all non-independent clans start with babies, children and teenagers who are unable to be killed until age 18. I don't know what happens if the clan only has under 18 members and all the adults are killed. I can go test it real quick.
Edit: The clan becomes destroyed if only children remain alive, with the children greyed out. It says the children disappeared (on the day the clan was destroyed).