How to be Deader than Dead

In progressive order of 'deadness':

• Mutilate the corpse such that it is beyond the reach of even hypothetical advanced medical technology.
• Destroy the brain.
• Kill their children and grandchildren.
• Kill the rest of their relatives.
• Kill everyone who knew they existed.
• Remove all references to them in physical records.
• Destroy their legacy - any buildings the built, organisations they founded, etc.
• Construct a causal graph of every influence that passed through the deceased. Systematically and surgically undo every influence they had on the local reality. Do so with as few side effects as possible - including side effects involving the agent doing the overkill execution. This will include destroying their own memories, minimising energy and negentropy use and dumping outputs irreversibly.
• Find a means of time travel to see to it that they never existed.
• (Kill anyone who grew up near a crack in time while you are at it!)
• Take control of the entirety of space and time to ensure that nobody else can ever harness time travel, undoing what you have done.
• Find a way out of the matrix. Destroy the matrix. And the backups.
• Repeat above as necessary.