Maps App and Contacts app - difficulty synchronising

Somehow, Iā€™ve made a category called ā€˜Friendā€™. Itā€™s not in my contacts app but it has come over into maps. I want to delete it. It only contains one contact. There seems no way to do it within the maps app and Iā€™ve tried to find the relevant mysql table so I can delete it manually but no luck. Any suggestions.