You have to get in the car, ignition on engine not running. Press and hold the button on the dashboard until it brings up the reset menu. Then scroll through to the rear brake pads options and press and hold. You may need to handbrake to be off.
Here is a video:
https://www.google.com/url?sa=t&sour...Kmu9OqxGPOJSJF
Depending on what the rear wear sensor is telling the car it may or may not reset.