Deleting channels in action

[soboyle]

Any thoughts on how to delete channels in an action? I sometimes create channels during editing, with the names blue_copy, red_copy etc., but when I run a flatten layer, it leaves these channels behind, so that I get errors when I try to write out to jpg in an action. I've tried creating dummy channels in the files used for creating the action, and deleting them, but if photoshop doesnt see that channel name while running the action, it generates an error and stops.
My goal is to batch process thousands of photographs to jpgs of various resolutions, and only about 5% of the photographs have custom channels.

[Jack Flesher]

If you flatten, it will delete layer mask channels but not regular channels.  

Not sure this will work as I have not tried it, but... try adding a delete channel step in your action after the flatten step, one each for the maximum number of custom channels in any image.  This will probably generate an error message in an image with only one custom channel if you have say three delete channel steps, but you can check the ignore error button in batch.