Bournemouth manager Eddie Howe left the club by mutual agreement after they dropped out of the Premier League.
The 42-year-old has led The Cherries in over 450 games in two spells spanning over a decade.
The Englishman, who is leaving after speaking with club officials on Saturday, said he believes it is "time for the club to make a change."
Bournemouth's five-year high flight ended despite 3-1 win at Everton on the last day of the season.
“After spending a total of 25 years at the club as a player and manager, this decision, made with the club, is one of the toughest I've ever had to make,” Howe said in an open letter to fans. ,
“However, while the affection and love I have for this football club will always last, we all feel together that now is the right time for the club to move in a new direction.”
"Bournemouth will always be in my heart, but I firmly believe that now is the right time for a change."
Bournemouth grew from League Two to become a recognized Premier League team under Howe, which led them to three promotions in six seasons.
But they lost 22 of their 38 games to finish 18th in the table, one point from safety and return to the championship after five seasons in the Premier League.
The big-money signature row didn't work for Cherry the way Howe – who has played over 250 times for the club – hoped.
Winger Jordon Ibe, who cost £ 15m from Liverpool in 2016 only played two league games in 2019-20, with striker Dominik Solanke who arrived in a £ 19 million deal from Anfield in 2019 – scored three league goals in 32 games
South coast club also suffered injuries, not least a seasoned defender Charlie Daniels dropped for the season august 2019 and a promising winger David Brooks requires two surgeries it saw him miss most of the campaign.
Cherries chief executive Neil Blake said Howe was a Bournemouth legend who helped "transform the club's identity and history."
He said the decision to part ways with the company was "even more difficult given our close friendship."
"What he achieved is a miracle."
Former Bournemouth boss Harry Redknapp, who ran the club from 1983 to 1992 and first introduced them to the second tier of English football in 1987, predicts that Howe will "soon be back in the Premier League."
He told BBC Radio 5 Live: “I am very surprised. I was confident that he would try to get the club back next season. The work he did was incredible. "
“He took the third level club into the championship – which was a miracle – and then into the prime minister, which I thought was impossible to do.
“Then for five years he made us play incredible football, beating everyone at different times – it was amazing.
“The stadium can only accommodate 11,000 people, they were not eligible to get into the Premier League. For 100 years, they never made it out of the third or fourth division. No disrespect, but it will be like Rochdale or similar clubs entering the Premier League. That was incredible.
“It won't be easy to follow him. He could no longer do this and leaves with his head held high. "
Howe's schedule as Bournemouth manager
December 31, 2008 Howe, just 31, takes over as caretaker for the 91st-ranked club in the Football League in the face of demotion and possible liquidation. Despite starting the season with -17 points, Cherries remain on the last day of the season after winning the last three games.
May 8, 2010 – Bournemouth promoted to League One in Howe's first full season as permanent boss, finishing second with 83 points.
January 14, 2011 – In his first season in the First League, Howe takes Cherries to the playoffs and hosts Championship clubs. He eventually leaves for Burnley. Bournemouth lose on penalties to Huddersfield in the playoff semi-finals.
October 16, 2012 – After 18 months without much success at Turf Moore Howe returns to Bournemouth. They are promoted to the Doncaster Championship. This is only the second time in the history of the club in which they have played in the two best tournaments.
2 May 2015 After finishing 10th in his first season in the Championship, Howe takes Cherry to the title by beating Watford on the last day. The season includes an 8-0 win at Birmingham and the promotion to the top flight is the club's first.
17 May 2016 – Bournemouth survived with a five-point cushion after the first season of the Premier League when they spent £ 10m on Benik Afobe and beat Chelsea and Manchester United.
May 21, 2017 Bournemouth finishes ninth in top flight and Joshua King scores 16 Premier League goals.
May 13, 2018 “In the relegation zone for Christmas, Howe is making an impressive recovery and Bournemouth ends up finishing in 12th place.
May 12, 2019 – Bournemouth at the beginning of December takes sixth place, but in the second half of the season fades into the background and finishes 14th – 11 points without problems.
January 1, 2020 – A 4-0 defeat at West Ham puts Bournemouth in the relegation zone for the first time in 2019-20.
July 26, 2020 – Bournemouth's five-year Premier League tenure ends despite beating Everton as Aston Villa tied for West Ham.
August 1, 2020 – Howe leaves the club by mutual agreement.