A physician is having single doctor clinic, only OPD. No admission facility or hospital/nursing home set up. He sees a troublemaker patient in his wating room who may harm the doctor or his OPD room. Can a physician reject such patient to treat?

Or the patient definitely needs hospitalization for some reason (say AMI, Gastro with dehydration, Alcoholic intoxication etc.) which the physician can not provide. Now does the doctor have freedom of not choosing such patient? What is the legal situation here? How should I handle such situations?