Like Drew said.
If that doesn't work, rebrew the beer using no/minimal cinnamon. Blend your old batch with your new batch in secondary (taking care not to expose your beer to oxygen). Rebottle. Wait.
Alternately, brew something different and blend. You can experiment by adding different amounts of a bottle of your cinna-beer to a glass of your other beers to get an idea of how a particular blend might work.
If that doesn't work, you've got the base for barbecue sauce or Cincinnati chili.
If that doesn't work, there are means of removing the cinnamon via "recursive condensation," which might not be legal in your country, state or municipality.
Anyhow, it ain't sink food just yet.