Cho, the chairman of South Korean conglomerate Hanjin Group, had been at the helm of the organising committee since August 2014 and was widely credited with bringing sponsors on board and giving stalled preparations for the Games a shot in the arm.
However, with Hanjin Shipping, South Korea's largest shipper by assets, facing severe financial difficulties, Cho needed to focus his efforts on restructuring and stabilising the company, POCOG said in a statement.
Cho's departure leaves organisers scrambling to find a replacement just 646 days before the start of Asia's first Winter Olympics outside of Japan.
"For the past two years, I have truly put forward my very best efforts to work with every member of the organising committee to prepare a successful Olympic and Paralympic Winter Games in 2018," he said.
"I give my assurances that I will continue to support Pyeongchang through to the Games in 2018."
The International Olympic Committee said it respected his decision and noted the progress in preparations made since he took over two years ago.
"There remain a number of important steps to be taken ahead of the Games and the IOC remains confident that through our close cooperation with the Pyeongchang 2018 Organising Committee these will be successfully addressed," it said in a statement.
"We look forward to Korea hosting excellent Olympic Winter Games in 2018."
Hanjin Group, which also controls the nation's flag carrier Korean Air, a corporate sponsor of the Games, said in a statement Cho would "devote all his energy to take care of current issues within the group, such as Hanjin Shipping."
"Even when returning to the group's management, Cho will not spare any effort and support for the successful hosting of the Pyeongchang Winter Olympics," it added.
NUT RAGE
Late last month, Hanjin Shipping said it would ask creditor banks to restructure its debt. It had debt of 5.6 trillion won ($4.92 billion) and a debt-to-equity ratio of nearly 850 percent as at the end of 2015, according to the company.
Cho had spearheaded Pyeongchang's bidding committee when it was awarded the Games in 2011 and the 67-year-old was praised for his devotion to the role, travelling the world to promote the South Korean alpine town's bid.
Kim Jin-sun's abrupt resignation as organising committee head in 2014 sparked calls for Cho to take over and while he was reluctant to do so due to concerns his business commitments took up too much of his time, he eventually ceded to the requests.
Cho's time as POCOG president was not always plain sailing, though.
Concerns about costs and construction setbacks raised speculation last year that some of the events might have to be moved away from Pyeongchang, perhaps even to Japan.
Cho also had much-publicised family issues to deal with in 2014 when his eldest daughter, Heather, forced a Korean Air flight crew chief off the plane because she was unhappy about the way she was served macadamia nuts.
The incident, dubbed the 'nut rage' case, stoked widespread ridicule, as well as outrage over the conduct of the country's powerful family-run conglomerates called 'chaebol'.
However, the POCOG chairman went some way to restoring his family's reputation by getting Pyeongchang preparations off the ground, pushing venue construction along and getting major firms Samsung and LG to pour in funds to support the Games.
South Korea's two biggest automakers, Hyundai Motor Co and its affiliate Kia Motors Corp, also signed on as sponsors, agreeing to provide vehicles and pump in cash to help with the running of the multi-sports event.
($1 = 1,137.8400 won)
(Reporting by Nataly Pak, Jee Heun Kahng and Joyce Lee; Additional reporting by Karolos Grohmann in Berlin; Writing by Peter Rutherford; Editing by John O'Brien)
