Retired? No, you’re fired!

The city has asked a judge to terminate a teacher who finally quit last fall after beating a rap for alleged sexual misconduct.

Steven Ostrin, 58, a once-popular social-studies instructor at the elite Brooklyn Tech HS, was found guilty in December 2010 of “sexual banter” after a two-year administrative trial.

Ostrin allegedly hugged and tried to kiss a female student; lewdly praised her skin, hair and neck; and talked about her performing a “strip tease” for him, among other charges.

Hearing officer Howard Edelman suspended Ostrin for six months without pay but refused to fire the “demanding and inspiring” teacher.

The Department of Education appealed, rehashing earlier charges that its prosecutors had dropped because they were unprovable. Ostrin remained on the payroll at $100,049 a year but was banished to the “rubber room.” He hasn’t taught since 2005.

The city doesn’t want Edelman’s ruling to set a precedent for leniency.