Rather than needing to "kill" or do weird favours for someone, why not just raise/lower property value to the point of the person needing to leave? Supporting local businesses, killing off undesirables, building better buildings, things in that sort would raise a areas value while Killing the good folk, smashing windows, and generally causing a ruckus would lower an areas value.
After a point the NPC'll either get mauled by a supercop or stabbed by a slum dweller. Either way it solves itself
