A Yale professor and his wife who became targets of protests for an email about potentially offensive Halloween costumes are resigning their positions as heads of a residential community at the university.

The professor, Nicholas Christakis, a sociologist and physician, announced on his Twitter feed Wednesday that he was stepping down as head of Silliman College, a residence where he and his wife served as social and intellectual mentors to students.

Dr. Christakis, who directs Yale’s Human Nature Lab, said they were not severing all their ties to the university. He will stay on as a tenured professor. His wife, Erika Christakis, who recently published a book about preschool, will continue her work in that field, he said, though he did not specify in what capacity. The resignations are effective in July.