The devblog states:
Kill rights are bought “on the spot” in space, i.e. if you select a player in space and that player has a kill right on him for sale, you can buy & activate (one action) it right then and there. This immediately puts a Suspect Flag on the target, thus allowing you and others in your vicinity to attack the target. If the target player is killed while under a Suspect flag, then the kill right is ‘spent’. If the target manages to escape and the Suspect flag timer (15 minutes) lapses, the kill right is still available to be purchased (activated) later on.So it would appear, the following would be a valid way in which to shed a kill right.
Sit on an undock in a nice blingy, shiny ship. Some 'tard will activate the kill right on you. Once the kill right has been activated, you will now have a suspect flag for the next 15 minutes. Dock at the station (you can wait until they aggress you, for more giggles.) Undock in a cheap ship. Self-destruct or wait for someone to kill you. Do not let the suspect timer run-down. Once your ship has been destroyed, dock up or warp away in your pod. Your kill right has been completed.
Of course, the whole undock thing is just baiting. If you're in space and not in a position to fight back, but do get away before being pointed, getting to a cheap ship should be the first priority. Don't try to run down your suspect timer. Find a way to get yourself into a cheap ship and get it exploded. The devblog doesn't state anything about how you have to be killed, just that you have to be killed while the kill right is activated. At that point the kill right is considered "spent."