Mary McAngus did not give any reason for quitting in her letter, The Columbus Dispatch reported. She was the mayor of Pomeroy, a village of fewer than 2,000 residents on the Ohio River in the southern part of the state.
Pomeroy Police Chief Mark Profitt had publicly criticized the mayor for her alleged treatment of Kyle Calendine, a homosexual hired as a part-time police officer.
Last month, Profitt warned the village council that the mayor put Pomeroy at risk of a discrimination lawsuit. In a six-page sworn statement submitted as part of an information packet, he said McAngus used an anti-gay slur about Calendine.
Some observers also said McAngus objected to Calendine's partner dropping in at the village hall, although relatives of other police officers are frequent visitors.
McAngus has made no public comment on the accusations.
Calendine said he wished the mayor had apologized. He said he hopes her resignation will reduce tensions in Pomeroy.
"I am who I am, and I won't apologize for how I live my life," Calendine said. "I just want to do my job."
Profitt was also happy about the mayor's departure.
"Kyle Calendine would lay down his life for anyone in need," the chief said. "This is a win for Kyle, for our department and for the gay community. It lets people know that no matter what, we're all in this together."