The club announced on Thursday that Foster had taken the decision to walk away, and Foster himself took to Twitter to explain the decision.
It has been a difficult season for Daventry, and the decision last month by chairman Iain Humphrey to slash the playing budget has led to a mass player exodus.
It is clear that Foster holds no grudges against Humphrey for that decision, nor does he feel any sort of ill-will towards the club, but he just feels he is not the right man to carry on in charge under the new financial constraints.
Foster has had to stand by as virtually the entire squad that went so close to winning the Southern League Division One Central - and also made the first round of the FA Cup last season - has left for pastures new.
“With deepest regret the time has come to stand down from my position,” said Foster on his Twitter feed @DarranDaz
“After failing on many signings to help our situation out, I feel the time is right to bring in a body who has the contacts to suit the financial situation.
“You can not lose this amount of players.”
Foster is clearly upset at having to walk away from Communications Park where he has been manager since 2012, and he was quick to thank the people who supported him throughout his management - particularly chairman Humphrey, and his loyal coach assistants Neil Champelovier and Jamie Gould.
“I will always have many good memories, and can only thank the chairman for those opportunities,” said Foster.
“I have to many people to thank for my time there so thank you to all who have supported me through our time.
“Of course, I thank the players for our success and memories, but special thanks to Neil Champelovier and Jamie Gould, who have been immense.”
Daventry, who are 13th in the Division One Central table with 20 points from 14 games, are without a fixture this weekend.