We used to live in Champion. We have since moved to SW Ohio, but have family in Warren.
Here is the page with a link to codified ordinances for Warren:
http://warren.org/city_officials/city_council/city_ordinances
Here is the wording about animals:
505.14 PROHIBITING THE KEEPING OR HARBORING OF CERTAIN ANIMALS WITHIN THE CITY.
No person shall own, keep or harbor any of the following enumerated animals at any premises or on any property within the corporate limits of the City: cattle, sheep, mules, goats, pigs, hogs, poultry, wolves, wolf dogs, timber shephards or wolf mixed breeds.
(Ord. 11647/03. Passed 1-8-03.)
So unfortunately it sounds like you can't have chickens in the city limits unless you could get some kind of variance or work toward changing the ordinance.