LOL, I had a very similar experience. Just stop responding to his quests, and eventually he will stop giving them to you. You can also move him to another settlement (Hangman’s Alley is my go-to settlement for the annoying NPCs).
16 posted on 06/13/2016 12:37:10 PM PDT by Scutter
Ha! I never thought of that! I will move him to Hangman's Alley tonight in fact. Can you assign him to something productive like tato picking, or does he just wander around?