Also, be very careful when unplugging other people. I know you were just trying to diagnose a problem, but one issue that could have come up is if that other Leaf's charge timer had to be overridden to get it to charge, if you unplug it, it will not charge again upon re-plugging unless the timer override is again activated. If the car is locked, you won't be able to do that.
Some charging networks like ChargePoint or Blink can notify you of unauthorized unplugging, but only if you enable it and submit a valid cell# or email address that you can view while away from the car. Same with the Leaf's CarWings system, but only if you have CarWings and have enabled this feature. Otherwise, the result could be that car's owner returning with far less of a charge than they expected.
And even if that Leaf owner did subscribe to notifications, you could find yourself having to 'splain yourself to a 6 foot 5, 300 lb Leaf driver why you unplugged him
Blue Ocean 2012 Leaf SV, lost that 1st bar at 34 months/26,435 miles. Lease returned 2 months later. Final LeafStat figures: 225 Gids, 17.44 kWH, SOC 91.89%, SOH 82.36%, 69.49% HX, 54.57 Ahr, battery temp 61.8 F.
Now driving a 2015 VW eGolf SEL.