The superintendent of Marlborough’s public schools, Maureen Greulich, is retiring after a 25-year career in the city’s schools. She began here as a substitute Latin teacher, and said she is leaving the post at the end of the school year to move closer to family. “Despite having another year on my contract, my husband and I have decided to retire and are building a home outside Indianapolis to be closer to our three granddaughters,” she wrote in an email to the Globe. Greulich, 63, stepped up as interim superintendent in July 2016 and was permanently appointed that fall. In the past dozen years, the district has seen seven different superintendents.“It’s hard to walk away,” she said in an interview. “It’s a great job.” A search for a new superintendent has not yet begun.Lucas Phillips can be reached at firstname.lastname@example.org.