Complex sentence: He worked as a high school football coach and teacher in the Middle Tennessee area at Shelbyville Central High School, his high school alma mater until 2006, he then left coaching to go into educational administration.
Split into simpler sentences: He worked as a high school football coach and teacher in the Middle Tennessee area at Shelbyville Central High School, his high school alma mater. In 2006, he left coaching to go into educational administration.