The surprise news arrives after he replaced Sam Ricketts in December.
Although recent results have been challenging, the Red Dragons won their last game at home to Maidenhead.
Wrexham sit in fifth place, but are just four points behind leaders Leyton Orient.
“Wrexham Football Club can confirm that Graham Barrow has resigned from his position as First Team manager,” a club statement read.
“Graham has been a major part of our season to date and leaves the club four points from the top of the league with fifteen games remaining.
“We would like to thank Graham for his efforts and contribution in his time at the Club and he leaves with our very best wishes.
“The club will make a further announcement tomorrow regarding a replacement First Team Manager.”