I’m not sure that would do anything. The centering ring adjusts to the led, not the other way around. It looks like the centering ring is just a tiny bit larger than the led body. He could probably try loosening the bezel that presses down on the lens and reflector so that they are loose and then tap the light against his hand to make the reflector and centering ring shift slightly. Once it looks centered, tighten the bezel back down.
Generally speaking, perfect centering gets harder and harder as the led die gets smaller. Just tightening the bezel again could shift the centering a little bit. Its going to be trial and error to get it perfect. If the centering ring refuses to move over, then you might have an issue of the mcpcb pushed to the side limiting adjustment. In that case I’d do like Sydney says and loosen and screws and push the mcpcb back towards the middle. Then you go back to the first procedure using light taps to shift the reflector and tightening it down.
An explanation of the parts:
If you take the bezel off you’ll see the lens and an oring. Remember how they are arranged. Then the reflector is sitting on top of a smaller plastic piece called a centering ring. The reflector centers on that. Then the hole in the centering ring is supposed to center around the led. It looks like the hole is just a tiny bit too large in your light which allows it to not center perfectly every time.
The pressure of screwing down the bezel presses down on the glass, oring, reflector, centering ring and mcpcb. This pressure is what allows good heat transfer from the mcpcb to the flashlight head. The mcpcb might have one or two screws going through it. These are usually there only to prevent rotation. Tightening the bezel might rotate the reflector and it could cut the wires if the mcpcb were to rotate.
If you unscrew the bezel and remove the downward pressure the parts should be able to move around a little bit.
Here is a typical centering ring.
It’s also called led insulation gasket or a reflector spacer.