You can:
reverse rotafix it
wrap a piece of old chain around the cog, put 2 short 2x4s on both sides of a vice, sandwich the cog between the 2x4s with the vise, turn the wheel as hard as you can
poor some triflow on it, wait 15 minutes, then hit it with the chain whip
start skidding around town and hope that it unthreads itself, aka suicide skid
ride for fun