Depends where you want to go. If you wanted to go to UCLA, UVA, Duke or Vandy, and you're sure you got <165 then cancel. Getting an average of two scores (where one is a 163 or something) up to those school's medians would require a score like 173 or higher. If you don't care and are confident you could do better, keep your score and find out what you got, retake if it's too low. NW and Cornell will take you with a 167-169 if it's your higher score.