Select the cell count manually (e.g. "10S") instead of selecting "Auto" and it becomes a non-balancing charger.
There is no mechanism to extend the charge voltage above 43.5 termination voltage (10S@4.35v).
You also cannot charge a 20s Pack as 2x 10S packs connected to each channel while they are connected in series; they would need to be disconnected between packs 10 and 11 before connected the 2x 10S packs to each channel.