An unhinged man slashed a cop in the wrist who responded to his Harlem NYCHA apartment this week, cops said.

Kevin Joseph, 32, was “acting erratic[ally] and behaving in a violent manner” around 9:30 a.m. Tuesday when cops showed up at his apartment in the King Towers on West 115th Street for an “emotionally disturbed person” call, police said. 

Police tried to take Joseph into custody so that EMS could remove him to the hospital, cops said. 

But instead of complying, Joseph became violent and pulled out a kitchen knife — slashing a 30-year-old cop in the wrist and puncturing her thumb, police said. 

The knife was recovered and Joseph was arrested and charged with assault and criminal possession of a weapon, cops said. 

The officer was taken to a local hospital in stable condition, authorities said.