Edwards said it was "mutually decided" that the former Sun editor would leave Outside "to pursue some other opportunities in the media, creative and digital areas". "It was a good three years and we all wish him the best in his future endeavours."
He said there were no plans to replace Mohan’s role at the London-based agency.
"There’s a lot going on in the New Year so it doesn’t mean we won’t recruit, but just not in the same position," said Edwards, who moved to the chairman position at Outside with Mohan’s appointment in September 2015.
Mohan refers to himself as a 'media and business consultant' in his updated Linkedin profile.
The award-winning journalist and broadcaster left The Sun in 2013 to work for parent company, News Corporation. He was at Rupert Murdoch’s media business for almost 20 years, working as The Sun’s showbiz editor and associate editor (features) before rising to editor in 2009.
Speaking to Edwards and Mohan for a profile last year, PRWeek reported that the agency founder focused more on music clients while Mohan was more heavily involved in crisis comms, with the two "meeting in the middle" on sport.
The agency generated revenue of £1.5m in 2017, a decline of 28 per cent on the previous year, according to PRWeek’s UK Top 150 Consultancies report. Staff headcount was 17.
Edwards, who has represented the likes of Prince, Bowie, the Rolling Stones, the Beckhams, Amy Winehouse and Naomi Campbell in a career spanning more than 40 years, was inducted into the PRWeek UK Hall of Fame in 2017.