Josh Smith, also known as Josh Smythe, led the Dunedin Fire and Circus Club and was the Otago University Students’ Association (OUSA) representative for clubs and societies, but stood aside from those roles in recent weeks.
He said standing down was not related to the allegation, which he understood was made to Critic Te Arohi student magazine.
The Fire and Circus Club is itself under scrutiny for what has been described as a culture of predatory behaviour.
OUSA is also inspecting the club’s finances.
A university spokeswoman urged anyone concerned about inappropriate behaviour at the club to contact police.
Police have not confirmed whether they are investigating.
Mr Smith said he was heartbroken about the complaint and he referred to a problem he had with alcohol, but said he had no memory of committing sexual offending.
"We are disappointed with Josh’s behaviour but recognise that the culture within certain clubs at the university reproduces this kind of behaviour," said Kayli Taylor, director of Thursdays in Black Otago, a student-led movement towards a world free from sexual violence.
"Allegations against Josh and the DFCC are not isolated but sit against a backdrop of repeated allegations of sexual assault, harassment and abuse on this campus."
She referred to allegations connected to the Knox residential college last year, among others.
"Sexual violence is — and remains — a significant issue on this campus, and across Aotearoa New Zealand."
Though not admitting guilt, Mr Smith said he had betrayed people’s trust. He had also been a victim of abuse.
"I have struggled with alcohol for most of my life ...
"However, this is no excuse for my actions.
"I apologise profusely to those I have harmed and those whose trust I have broken."
The complaint against Mr Smith followed a survey carried out at the DFCC that revealed a problematic culture at the club.
A review recommended a change of leadership and Mr Smith stood down as president at the start of this month.
OUSA chief executive Debbie Downs said the association would review all clubs and societies "to ensure all conduct is of a standard expected of affiliated groups".
"We are also in the process of implementing a complaints policy that will cover sexual misconduct within clubs and societies."
Nominations for Mr Smith’s replacement as the OUSA clubs representative closed yesterday.
The fire club is affiliated to OUSA, rather than the university, though that affiliation has been suspended amid an investigation.