The boys at PCReviewspot post their Logitech Mouse LED modification guide.
After removing the small metal brace, take that plastic piece
that it was holding down (this is the Led mount) and bend it upward just a bit,
this will make it easier to remove the Led. Now, turn over the circuit board
and look near the very top right under the start of the Led mount where the
Led wires feed into the board. There are two solder points which you will need
to re-melt with your soldering iron and pop out the Led wires by pulling on
the mount while the solder is molten. It shouldn't take more than a few tries
before you can wiggle it out.