Unless you have a written contract detailing your specific role and job duties, you are at his whim. I refer to a contract and not a job description.
As Ohio is an "employment at will" state, you can be fired for any reason so long as it is not an 'illegal" termination. http://research.lawyers.com/Ohio/Employment-Law-in-Ohio.html
I would strongly request a face to face meeting with your boss, and his boss, to discuss your displeasure with your change in roles. You walk a tight rope if you approach this in any other way but cordially and professionally.