Agar, who was in his post for two and a half years, stepped down in the wake of his club’s 20-12 defeat to Super League relegation rivals Bradford on Sunday.
Agar succeeded John Kear at Wakefield in October 2011 and defied expectations by guiding them to a play-off spot in his first campaign on the back of a club Super League record run of seven successive wins.
He achieved that improbable success despite being forced to bring in 20 new faces and was faced with a similar task at the end of last season when financial difficulties forced the club to shed several high-profile players. The Wildcats have won just four of their 15 matches so far.
Agar said: “I spoke with the board of directors a number of weeks ago outlining the reasons why I had decided to look for another job within the game at the end of the season and therefore requested a release from the remaining two years of my contract.
“All parties felt that with a new coach being decided upon and the club entering the recruitment period, it would be hard to continue in the role, especially with the players knowing I was going. It would also allow James to start putting into place his plans.
“Hopefully, the club will be in a position in the near future to provide stability and consolidate their position in the top flight and give James the resources he needs to be successful.”
Leeds full-back Zak Hardaker is to be investigated over allegations that he made homophobic comments during the Rhinos’ 24-6 Super League defeat at Warrington last Friday.
Hardaker is alleged to have mouthed a homophobic reference towards referee James Child which has been referred to the RFL’s compliance department.
Hardaker’s team-mate Carl Ablett has been charged with a grade C offence of kicking Warrington centre Joel Monaghan in the act of scoring Wolves’ final try in the same match.
Hull KR’s Michael Weyman is facing the threat of a second suspension this year after being accused of using foul and abusive language towards a match official in his side’s defeat at Castleford.
Wakefield’s Richard Moore has been charged with a grade B striking offence during the 20-12 defeat at Bradford, while Bulls’ Elliot Kear has submitted an early guilty plea to a grade A striking offence during the same incident.