Earth everyone on earth learns that they are in a simulation, and your everyday Joe Shmo suddenly learns that he can control the flow of time. He can advance himself forward or backward in the simulation, allowing him to manipulate the world as he wishes.
So, Joe decides to test his powers. He goes back in time and breaks a window in his apartment. But, when he returns to the present, the window is unbroken. Everything Joe does directly in the past, by his own hand, is undone when he leaves that timeline. So, if Joe shoots someone, they won't be dead in the future. He can't kill his grandfather to delete himself. The timeline when he enters the world ends when he leaves and everything there continues as if he never intervened.
What is the most reliable, repeatable, and easiest way to kill people indirectly?
Joe is not very remarkable. He's not buff, he doesn't have contacts with the mob, nothing out of the ordinary.
Joe isn't worried about what else happens to people, just that his target is dead. Casualties happen.
Joe and his target live in the Simulated New York City, or another city of about the same properties.
Only actions Joe can directly control are undone. Ramming into someone won't work, but blowing up the building the person is in will. He could control the car, but he couldn't control the falling rubble.