In the following picture (Fig-1), you can observe that the built-in LED1 is connected with DPin-D4 with which you have also connected the signal pin of your Servo.
If you don't want to the see the ON condition of LED1, then connect your Servo to any other DPin.
Well that worked like a charm!
Pretty easy!
I guess I need to study this board closer.
How did you know that the LED was on D4 and the second LED was on D0? I haven't figured out the different pin identifications yet.
By calculative and non-destructive trial-and-error approach learned from many years of field experience in troubleshooting and repair of proprietary well-logging tools/instruments.