Once you've deleted it from your developer account, I think you're out of luck, unless someone at Roku can actually help you out.
For future reference, the best thing to have done would probably have been to publish an update to the channel that disabled it and displayed a message to the user, waited a few days to ensure everyone got the update, then remove it from the channel store.
My Channels: http://roku.permanence.com - Twitter: @TheEndlessDev
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