I know that it have been few years sinse the original post, but for those who will find this artickle when searching for how to turn off the LED on Vertical Mouse 4 I'll put the answer from the manufacturer's site here:

1. Unplug VerticalMouse 4 when the computer is on.
2. Press and hold the – end of the Pointer Speed button and plug in the USB connector. If your mouse is a later production unit, it will turn off.To turn on the logo again, press and hold the + end of the Pointer Speed button when you plug in the USB connector.