It sounds like your insurance company might have determined during the investigation of your hit and run claim that the individual should have been a driver on your insurance policy. If the person lives in your household or occasionally drives your vehicle, some insurance companies might require the relative or friend to be added to your policy to cover any future claims.
If the driver does not drive your car on a frequent basis you might be able to ask the insurance carrier to remove him or her from your policy. To find out the specific reason your insurance company added the person to your policy, you will have to contact your insurance agent to ask. If you do not agree with their reasoning you can contact your state's insurance regulatory body to make sure that adding this person as a driver to your policy, without your permission, is allowable according to state insurance laws.