You could go inside the box and disconnect the LED, but obviously that would void the warranty on a new unit and it's not to be recommended if you're not used to working on such equipment. Depending upon the internal design, you might be able to just remove the cover and stick some black tape on the
inside though, between the LED and the front panel.
They are pointless and take up loads of energy!
Individually, they take very little. A typical LED standby light might consume about 20mW (that's 0.02 watt).