First-team coach Jim Troughton is leaving Warwickshire following a review of the 2020 season.
Troughton, 42, took over as first-team coach at Edgbaston in 2017, having been with the club as a junior and then senior player since the age of 11.
He said he was sad to "no longer be part" of the club's "vision". "It is with great sadness I will be leaving," Troughton told the club website.
Winter training will be managed by director of cricket Paul Farbrace.
He will assisted by bowling coach Graeme Welch, batting coach Tony Frost and second-team coach Ian Westwood.
Recruitment for a replacement Troughton's replacement will begin shortly, the club said.
The Bears were T20 Blast runners-up in 2017 and won promotion back to Division One of the County Championship in 2018, but Troughton said two "frustrating" seasons had followed.
Warwickshire finished third in their Bob Willis Trophy Group in 2020 with no wins and four draws from their five games, while they also placed third in their T20 Blast group.
Troughton added: "An injury-hit 2019 and a Covid-hit 2020 have most definitely affected the consistency on the park and our ability to move forward with results.
"Creating two England players and two England pathway players, as well as seeing the emergence of a promising number of academy graduates shows we now have a young and exciting squad taking shape and I have no doubt they will, in time, produce a consistent level of success in the years to come.
"I'm just sad I'm no longer part of that vision moving forward."
Chief executive Stuart Cain said: "Jim has been an excellent servant as a trophy-winning coach and player who captained the Bears to the County Championship in 2012.
"He will be missed by all at the club, but we wish him well. He will always be part of the family and welcome at Edgbaston any time."