There is no easy way. There is no FACTORY RESET button.
The only way to get the remote back to factory settings is to manually relabel the DEVICEs on the MAIN screen and then apply the AUX 155 device to all of the devices. It actually has 2 IR codes, but is the closest to actually deleting all of the codes.
If I remember correctly, you still have to delete all of your learned codes and macros manually.
