Erasing Channels
WARNING: This page is about a different car, the 2010 GMC Sierra, 2010 GMC Cab & Chassis Sierra, 2010 Chevrolet Silverado, and 2010 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
To erase programmed channels, press and hold the two outside buttons until the lights on the GDO transmitter begins to flash. Once the LEDs begin to flash, release both buttons; all learned codes are now erased.
Individual channels cannot be erased, but can be reprogrammed using the procedures above.