If you mean by "report a doctor" to report that a doctor has done something wrong to you then you, report the wrong doing to the state agency that licenses doctor in your state. It could be called The Board of Medical Licenser, State Board of Medicine, The Medical Board of Registration or something similar. If you type your state name and the words "medical license" in the Google Search box you will get the correct list. If you want to report a doctor who has committed a crime, make the report to your state police bureau of investigations. In any event, it is usually more effective to make your report to a state rather than to a local agency. You could make your report to the the local "Medical Association" or "Medical Society" but these organizations usually do not have the power or authority to punish a bad doctor.