David Sullivan announced Saturday he had stepped down from his role as joint-chair of West Ham with immediate effect.
The 77-year-old is leaving his role of 16 years to fight "false allegations" about his private life.
Sullivan, who built a business empire from owning pornographic magazines and sex shops, said: " I have recently become aware that factually incorrect and entirely false, decades-old allegations concerning my personal life are due to be broadcast and published."
He added: "The false allegations levelled against me have been sensationalised by the media. After a lifetime spent building businesses in the adult industry, in which I have met thousands of women, it is sadly inevitable that a small number of improper conduct claims are being made against me. I categorically deny these claims."
Sullivan and business partner David Gold completed their takeover of West Ham after selling Birmingham, and brought Karren Brady with them as vice-chairman.
Their tenure oversaw the unpopular move from Upton Park to the former Olympic Stadium in 2016, making the three of them the focus of numerous anti-board protests among club’s supporters even before the club were relegated from the Premier League this season.
"I am a private man, and those who personally and professionally know the real David Sullivan, not the caricature invented by the tabloids, know exactly who I am and what I stand for," Sullivan added in his statement.
"This has been an incredibly painful decision to make, but it is one made out of love, respect, and responsibility toward a football club and a fan base that deserve absolute unity and focus moving forward."
West Ham said they will give "an update on the future structure of the board of directors in due course, but will make no further comment at this time".
Czech businessman Daniel Kretinsky bought a 27 per cent stake in the London club in 2021 and is reportedly set to increase his holding.