Trimming an aluminum emitter board

Would trimming this from 16mm to 15mm be possible or not?
I do see the power leads and solder pads and I realize that damaging that would ruin the board....but otherwise?

The thing to watch out for is if you do trim into the solder pads or power traces just make sure there is no continuity between them and the bottom of the board. Other than that you can trim it as small as you need. You can check continuity with a digital multi meter.

+1 what light-modder said.

Anodizing provides some degree of electrical resistance that is loss once fresh aluminum is exposed. In addition to shorts during the initial installation, one needs to be mindful of long-term rubbing risks to the lead wires as well.

My first priority is always to get a smaller MCPCB if possible, trimming takes time and is difficult to finish as nicely as factory. But sometimes boards need to be trimmed to fit odd shapes. I coat over my exposed edges with epoxy (I use CW2500 Epoxy Overcoat) to minimize the risk of wire short to the board.

Sometimes when trimming odd shapes I need help with re-centering the emitter afterwards. On those occasions I find those LED spacers that surround the dome to be a great help.

It looks like it is possible.
Use a rotary tool (like a dremel) and some abrasive roller (like a sanding roller or diamond grit roller, the gutter bits may damage the board or be hard to control)
If a dremel is not an option use sandpaper.

As light_modder and pc_light said be careful of exposed traces.