The 58-year-old moved from his position as chief executive to director of football earlier this year.
Spireites director Ashley Carson said the role was now "redundant".
Turner, who joined Chesterfield in 2011, told the club website: "I am very disappointed to be leaving Chesterfield, but I can understand the situation and I leave on good terms."
Chesterfield director of football Chris Turner has left the struggling League One club.