Simon Halsey resigned as manager of Southern Counties East Lordswood on Saturday after less than a year in charge.
Halsey's resignation followed the 3-0 defeat at Whyteleafe - their fourth successive league defeat.
Halsey said: "My time there was done. It was nothing to do with recent results. It gives the club a chance to get somebody in and build for next season.
"It's the first time I've quit in my 18 years as a coach or manager but I just felt that the time was right and there's nothing in the pipeline."
Lordswood vice-chairman Paul Caulfield said: "Everyone at the club would like to thank Simon for his efforts during his time at Lordswood.
"We are now making efforts to search for a new manager to get us through to the end of the current season and potentially build for next."
Halsey, who took over from former boss Jason Lillis at the end of last season, transformed the squad in the summer and they did enjoy a notable win over Whyteleafe in the FA Vase and have beaten high-flying Ashford in the league this season.
But Lordswood lost out to Fleet Leisure in the Kent Senior Trophy and were knocked out of the FA Vase by Hanwell Town.