Update:
One my Test-PC turning off the dolphin bar with "DevCon" didn't work. The driver was disabled, but the LEDs were still on.
For this case I also found a solution. I just attached the DolphinBar via an external Mini-USB Hub. They are available starting from 5€.
Then I used the VID/PID of the "USB Root device" in the batch files instead of the VID/PID of the DolphinBar. As soon as the Hub was turned off, the DolphinBar LEDs were dark.
One my Test-PC turning off the dolphin bar with "DevCon" didn't work. The driver was disabled, but the LEDs were still on.
For this case I also found a solution. I just attached the DolphinBar via an external Mini-USB Hub. They are available starting from 5€.
Then I used the VID/PID of the "USB Root device" in the batch files instead of the VID/PID of the DolphinBar. As soon as the Hub was turned off, the DolphinBar LEDs were dark.