Coates, the former boss of England Netball, was only appointed in March 2020 but oversaw Great Britain’s worst Olympic Games in athletics since 1996.
Symington, a former Team GB cyclist who competed at the 2000 and 2004 Olympics, was appointed even more recently, in August 2020, and returns to her former sport.
She takes over a newly-created role as head of the Olympic and Paralympic Programme for the Great Britain Cycling Team (GBCT).
Mark Munro, current UK Athletics development director, will take over as interim CEO for six months and will work with the board to start the recruitment process for both roles.
UK Athletics chair Ian Beattie said: “I’d like to thank Jo and Sara for their work during their time at UK Athletics and I wish them both all the best for the future.”
On Symington’s new job, GBCT performance director Stephen Park commented: “Sara is renowned for her ability to lead sports teams and deliver results, not to mention her knowledge of Olympic and Paralympic sport.
“So she is the perfect addition to the GBCT as we seek to continue our legacy of success with wider social impact at Paris 2024 and beyond.”
Coates’ surprise departure is just the latest development in a tumultuous period for the organisation, which has faced scrutiny over Mo Farah’s association with disgraced coach Alberto Salazar and has lost its principle broadcast deal with the BBC.
It also comes after a difficult summer culminating in Team GB’s worst Olympic athletics performance in 25 years as they left a Games without a gold medal for the first time since Atlanta 1996, though there were encouraging performances from some young athletes in Tokyo, in particular Keely Hodgkinson and Josh Kerr, who won silvers in the women’s 800m and men’s 1500m, respectively.
The men’s 4x100m relay team missed out on gold to Italy by just 0.01 seconds, but could yet be stripped of their silver medals after sprinter CJ Ujah tested positive for two bad substances.
Reports last month claimed that a number of athletes had told World Athletics president Sebastian Coe after the Diamond League meeting in Zurich that they were unhappy with the current regime and urged him to intervene.
Additional reporting by PA.