Sam Allardyce will step down as West Brom manager at the end of the season.
The boss had held talks with the Baggies following their relegation from the Premier League and will leave after Sunday's finale at Leeds.
Allardyce replaced Slaven Bilic in December but had a break clause in his contract which could be activated if Albion, who are second bottom, went down.
They were relegated back to the Sky Bet Championship earlier this month and, following Wednesday's 3-1 defeat to West Ham, Allardyce confirmed his impending departure.
He said: "West Bromwich Albion made me a generous offer to stay at The Hawthorns that shows the commitment of an ambitious club. After serious consideration I have decided not to accept that offer.
"If I were to stay and achieve promotion next season the expectation would be for me to continue for at least another season and, sadly, that is not a commitment I feel able to make at this stage of my career.
"I believe the club now needs stability and continuity and this would, in my opinion, best be provided by a young and ambitious manager who can get us back to where we should be as an established Premier League football club."
Albion are second bottom of the Premier League and have won five games all season.
Sporting and technical director, Luke Dowling, said: "Sam, Sammy (Lee) and Robbie (Stockdale) came in at a really difficult time for the football club and worked tirelessly in their efforts to keep the club in the Premier League.
"Unfortunately, collectively, we were unable to achieve our goal of surviving relegation. In the second half of the season we played with passion and desire, delivering some memorable results with organised, entertaining football.
"Ultimately, we were unable to accumulate the points total required to keep us here, but Sam certainly restored pride with a number of resilient displays.
"Sam, Ken (Chief Executive, Xu Ke) and I have discussed at length our plans for the future and we very much hoped to have Sam in charge for next season and beyond.
"Sam and his coaching staff have been excellent to work with and I would like to thank them all for their efforts.
"Sam has given his reasons for leaving and we respect his decision. He has been brilliant to work with and I wish him, Sammy and Robbie all the very best in the future. They will always be welcome at The Hawthorns."
