Well shit. I’ll just bomb the family every start of the loop.
See, the problem is this is like trying to kill Pun-Pun. If I had a Reset whenever I want, Technically, I could never lose.
Let us turn it around:
Is there any way of this person to UNDO having a reset?
See, the problem is, this guy has a reset point. He can Move up the reset point, but he can never go back to a previous reset point. Eventually, we are going to have a situation where the entire universe is stuck in a loop where NOBODY can get free. Why? Because sooner or later, he will die of old age.
When that happens, he blips back to his last save. When was that? 20 years ago? 100 years ago? 10 minutes ago? IT DOES NOT MATTER. We are now STUCK in a loop that can ONLY get smaller. THE ENTIRE UNIVERSE IS STUCK, no matter what.
The only solution is to explain this to the person. To explain that no matter what he does, he will eventually die and... then reset... and nothing he has done will have any meaning. Nothing he does has any purpose. The only solution, THE ONLY WAY HIS LIFE CAN HAVE MEANING... is that he eventually has to die and stay dead.
So, the question then is, What sort of world will outlive him? What sort of legacy will he leave behind? He can create a near perfect world, but it will only be perfect up to the moment when he finally stops living and the world DOESN'T reset.
How can he get married? How can he have children? If he has a child, but he reset to before it's conception, it will never be the same child. He will NEVER impregnate his woman with the EXACT SAME SPERM on any reset that goes back before he did the dirty. Then this applies to ANY CHILD CONCEIVED during a loop. Yes, time resets and anything that happens is the same except what HE does, but I promise you, he will have an affect on the world. A few minutes won't be a problem. but a few days, a few weeks, a few years? HE WILL BE WIPING PEOPLE FROM EXISTENCE, sooner or later.
And then there is the way he will eventually die and destroy the entire world. How So?
Every time he goes back in time, he remembers what happens. Well, MEMORY IS STORED AS ENERGY.
So, either his brain has a finite amount of storage space, so eventually he will be wiping out his own memories and eventually destroying himself by wiping out his own personality. (Trust me. I know how this works. I have progressive memory loss. You'd be surprised how deleting just a few foundational memories can radically change who you are.)
OR... (and this is the worst case scenario)
He remembers EVERYTHING from each loop.
Why is that a problem? Because memory is stored as energy. So, the more memories you have, the more energy must be in your brain. The more energy in your brain, the more it is going to be a problem with each loop. EVENTUALLY, you are going to have so many memories jammed into your brain with each loop, that your brain starts to overheat. You will eventually reach a point where you will faint immediately after each loop. And god help you if you reach the point of BRAIN DAMAGE. Then you won't be able to STOP the loop. And so, eventually, you will die, and blip back in time, AGAIN, and AGAIN, an AGAIN...
Each blip carries back more energy. Each blip making a larger amount of build up in his mind. Each blip overheating his brain more and more. Each blip will get worse and worse until, eventually, you will reach a point where upon bliping back, his brain will explode.
Then we have a 2 second loop, according to the rules, where the Time looper loops, his head explodes, and 2 seconds later, he goes back in time and explodes again. Each loop adding on just one more planck moment of information, and each planck moment building upon each other.
Eventually, we will reach 4.16 x 10^46 degrees and the mind will achieve a Klugleblitz singularity and collapse into itself.
IF WE ARE LUCKY, this will create a closed loop in time-space, and being closed in time space, the singularity will no longer drag the rest of the universe along with it. It THAT happens, since singularities evaporate, and the singularity will be formed by inching up on the threshold of singularity one planck moment a loop, the singularity will then immediately evaporate. There will be a rather intense blast of Cosmic rays and chances are it will go off like a Tzar bomb. Which while killing everything out to the horizon, will be limited by the curve of the earth and thus the planet will survive.
IF WE ARE NOT LUCKY...
Well... the looping continues until the entire planet is sucked up into the singularity and a black hole the mass of earth will be our headstone. A small twisted bit of Time Space as the only monument to where we all used to live and love and laugh and play. On the upside, the moon will continue on just as it always has, orbiting where we once were. The gravitational collapse is unlikely to absorb anything outside low earth orbit. Anything at Geosynchronous orbit or further out will probably survive... for a while, at least.
AND SO... My method of killing this guy?
I'd just explain all this. I would explain how the longer he lives, the worse it will get and once it reaches the point he cannot "loop" and retain his mental faculties, the planet will be doomed. If he doesn't willingly end this before that point, nothing he does will matter. EVERYTHING HE TRIES TO BUILD WILL BE REDUCED TO NAUGHT BUT ASH.
So... why don't you figure out what good you can do with what time you have left, then check out in a way that lets everyone remember you as a hero, instead of being the ticking time bomb that will eventually, by the inevitable march of thermodynamics, result in the destruction of everything and anything that would leave behind any sort of record that you ever existed.