Edwards announced his departure in a statement on Orient's official website and the Sky Bet League Two club are now looking for their fourth manager of the season.
"It is with regret that I have made the decision to stand down as manager of Leyton Orient FC," Edwards said.
"It has been a very difficult decision but I feel that it is in the best interests of my career and my family.
"I have been offered and duly accepted a role working within the coaching department of the Football Association.
"It has been an honour and a privilege to have worked for the club for over seven and a half years.
"I thank the chairman for the opportunity to manage the team and I thank all staff, players and supporters for the backing that they have given to me in my time here.
"It goes without saying that I wish Leyton Orient FC every success in the challenge ahead and in the longer-term future."
The 45-year-old Edwards leaves Orient with the club in the relegation zone following Saturday's 2-0 defeat at Mansfield.
Orient have lost their last four games and Edwards oversaw only two wins in nine matches after succeeding Alberto Cavasin on November 23.
Edwards previously had a two-game spell in caretaker charge following the dismissal of Andy Hessenthaler at the end of September.
Orient have promised a statement on the managerial position at the club "will be made in due course".
Source : PA
Source: PA