Truro City have sacked manager Steve Massey with the club in 19th position in the Southern League Premier table.
Owner Peter Masters said he had offered Massey the chance to stay at the club in a "more passive" position, which the 55-year-old had rejected.
Truro have won just 10 league games all season and suffered early exits in the FA Cup and FA Trophy.
Massey, who replaced Lee Hodges at the helm in June 2013, was in his third spell in charge of the White Tigers.
"I felt the existing management had taken the team as far as it could and there was a need for change now if Truro City are going to make a serious challenge to win the league next season and gain promotion back into the Conference South and beyond," said Masters in a statement.
"Steve was given an option to remain at the club in an alternative, more passive, position which I thought would be beneficial to Steve and Truro City.
"This offer was not accepted and I must respect that decision. Therefore Steve Massey and his management team of Graham Kirkup and Glynn Hooper have now left the club."
Truro have been attempting to rebuild this season after financial problems left them in disarray and unable to pay players' wages.
City were relegated from the Conference South last season following a year that saw the club go into administration as former owner Kevin Heaney went bankrupt.
Masters, and fellow businessman Philip Perryman, took over the club last October, with Massey one of their first appointments.
The club had embarked on a policy of bringing in younger and more local players, in stark contrast to the previous approach of signing players such as ex-Premier League striker Barry Hayles.
Poor results forced Truro to sign several more experienced players, but the expected sustained improvement in form did not materialise.
"It's a sad day for me, Philip and all at the club but I honestly feel the timing is right for all parties," added Masters.
"Steve leaves with his head held high in the knowledge that Truro City are in a better place now than we were 18 months ago and for that we all owe Steve our gratitude for the part he has played.
"I am sure that I speak for all of us when I wish him all the very best for the future. I am confident Steve will emerge again in football somewhere in the south west.
"Moving forward, the bumpy journey continues, we have 10 tough matches left to play this season and 30 points to win. Truro City are not mathematically safe from relegation at this time and nothing must be taken for granted, therefore we must concentrate now on gaining points and building the foundations for next season to fulfil all of our ambitions.
"It is times like this when the true supporters of Truro City are at their very best I would now ask you all to play the 12th man as together we can truly achieve success on the pitch in a sustainable manner."