The Police Commissioner  is the highest-ranking official in the New York City Police Department as of 1984.
Primary Canon History
During the Gozer incident, the Police Commissioner was called to Mayor Lenny's office. While concerned, he also had no answers for the phenomenon manifesting but didn't seem to be in a panic unlike others in the Mayor's office. He informed the Mayor they blocked bridged and roads in response to the chaos. Once the Ghostbusters were summoned to the meeting, the Commissioner restrained Walter Peck after a certain insult was issued. When things settled, the Commissioner questioned Peck's declaration the Ghostbusters were frauds by pointing out a report of bleeding walls in the 53rd precinct. He and the Mayor's Aide soon escorted Peck out of the office.
Secondary Canon History