Yes. In every NBA contract it says, “The Team may terminate this Contract upon written notice to the Player if the Player shall at any time, fail, refuse, or neglect to conform his personal conduct to standards of good citizenship, good moral character (defined here to mean not engaging in acts of moral turpitude, whether or not such acts would constitute a crime), and good sportsmanship, to keep himself in first class physical condition, or to obey the Team’s training rules.”
However this rarely happens and is probably much more difficult than it seems.