Ex-Newcastle United captain relieved of managerial duties at Leyton Orient
The 33-year-old former Bolton, Newcastle and West Ham midfielder has been in charge at Brisbane Road for just 15 games after taking over as player-manager in January.
But his assistant Andy Hessenthaler will take charge when the O's face Dagenham on Saturday.
Orient CEO Alessandro Angelieri said in a statement.: "Everyone at the club is fighting hard to make sure we reach the play-offs this season.
"Whilst that aim remains within reach, we have decided that Kevin should focus entirely on his playing contribution until the end of the season.
"We believe that Kevin will be able to make a bigger impact on the team without the distraction of managerial duties.
"Andy Hessenthaler, who has been assisting Kevin over the past few months, will take charge of the first team in the interim."
Nolan - who captained Newcastle United during his spell in the North East - is the sixth managerial casualty in less than two years since Francesco Becchetti took over the club.
The Italian owner has previously overseen the departures of Russell Slade, Kevin Nugent, Mauro Milanese, Fabio Liverani and Ian Hendon, who was axed in January.
Nolan's managerial career began promisingly after five wins in the first seven games as the O's, relegated last season, climbed into the League Two play-off spots.
But they have taken just one point from their last four games and slipped to 11th after Saturday's 3-0 defeat at Barnet.