IAAF president Lord Coe has ended his 38-year ambassadorial paid role with US sportswear giant Nike.
It follows conflict of interest claims over the 2021 World Championships going to Eugene, Oregon, where Nike is based.
Athletics' governing body said Coe could remain in the role but he said it was "a distraction to the 18-hour days we are working to steady the ship".
It comes amid a recent wider doping and corruption scandal in the sport, which Coe has vowed to clean up.
Speaking at a news conference in Monaco following an IAAF council meeting, Coe said of his Nike role: "The current noise level around it is not good for Nike or the IAAF."
Coe also announced he would resign as British Olympic Association chairman after the Rio 2016 Olympics.
A BBC investigation revealed this week it had uncovered emails suggesting that when Coe was vice-president of the IAAF, he lobbied former president Lamine Diack with support for Eugene.
|BBC sports editor Dan Roan in Monaco:|
|Ever since Lord Coe became the most powerful man in athletics earlier this summer, he's faced tough questions about whether or not it was right that he retained a paid ambassadorial role for Nike, worth we think £100,000 a year.|
|Those questions only intensified this week when the BBC obtained an email that appeared to show Coe had been in discussions with a senior Nike executive over a bid for the 2021 World Athletics championships for Eugene.|
|The calls for Coe to quit his Nike role mirror that of the sportswear giant's slogan, "Just Do it". Tonight Coe did exactly that and he'll hope it enables him to concentrate on recovering the sport from doping and corruption scandals.|
|But many will ask why it took so long to get here, and whether Coe would have reached this decision without the BBC's revelation earlier this week. The fact it seems to have been made under duress, a matter of pragmatism rather than principle, leaves him open to criticism. Coe was known for his speed as an athlete, but the delay in cutting ties with Nike may have caused yet more damage - to both the sport - and its leader.|
The US city was awarded the 2021 World Championships in April without a bidding process, despite interest from the Swedish city of Gothenburg. Coe was elected IAAF president in August.
When asked about the allegations earlier this week, Coe told the BBC he "did not lobby anyone" over Eugene's bid, but "encouraged them to re-enter another bidding cycle as they had a strong bid".
At Thursday's Monaco news conference, Coe said: "I have sought advice from the IAAF's ethics committee to review my interests and was told I could retain my positions in Nike and [sports marketing company] CSM as long as I do not seek to influence any decisions that could influence them.
"I'm grateful for that advice but it is clear that perception and reality have become horribly mangled.
"I've made the following decisions: I've stepped down from my ambassadorial role with Nike which lasted 38 years."
He also announced sports marketing company CSM, for which he is executive chairman, would not tender for any IAAF work during his reign.
However, Culture, Media and Sport select committee member Damian Collins said Coe still had questions to answer.
Conservative MP Collins, who had called on the peer to cut his ties with Nike, said on Twitter doing so was "the right decision".
But he added: "Even though Seb Coe has given up his Nike job there are still questions to answer about the awarding of the Eugene 2021 World Championships."
Labour's shadow sports minister Clive Efford was also critical of Coe and said: "Seb Coe is a member of the House of Lords and a former MP - and as such he should know all about standards in public life and conflicts of interest.
"So it is disappointing that he waited until he was forced to resign from his position as an ambassador for Nike particularly when he needs to be seen to have clean hands in order to deal with corruption in world athletics."
But Toni Minichiello, who coaches British heptathlete Jessica Ennis-Hill, gave Coe his backing.
"I think he is the best candidate we have and the best person we could have put forward for the role from Britain," Minichiello told BBC Sport.
"The positive moves he has made today [Thursday] enforce that, and hopefully from here athletics can be viewed in a more positive light."
|Coe's key announcements|
|Ends 38-year paid brand ambassador role with Nike|
|Will step down as BOA chairman after 2016 Rio Olympics after almost four years in position|
|His CSM sports marketing company will not bid for IAAF contracts during his presidency|