How to dim LED light?

a black marker pen, a tiny dot in the center of the led. You can experiment with larger dots till you get it right. A Q-tip will rub it off. (assuming the led is glass)

Pop the cover and disconnect the line.

Purchase a small colored roll of thin tape. Cut a tiny square or circle big enough to cover most/all of the light. If you have a blue LED, you get an interesting purple color if you use a red tape. If you only cover the center portion of the LED, then it can look even nicer.

-IMO

Yup. Easy solution is to get a couple of inches of taillight repair tape (red or orange) at an auto parts store for $2-3. I use this effectively to tame the big bright Magnum Dynalab's display. A little red film makes the yellow display a nice muted orange. Have fun.

how about doing this the *right* way: solder splice a 1/4 watt resistor in series with the LED. Experiment with resistor values until you find the preferred intensity, or use a variable pot around 1k-ohm. If using fixed resistors, start out around 50 to 100 ohms & step up in ~100 ohm increments until you find the right one. Clip leads will come in handy until the best value is found; then just solder it in. Or install small signal diodes in series (watch polarity) you'll drop about 0.7 volts per diode. Really easy.