Uber doesn’t announce the reason as well as who would replace Dang Viet Dung. Uber Vietnam confirrmes to release more information as soon as possible.
Dang Viet Dung, 32, had spent three years running Uber Vietnam since the US–based firm entered the Asia country in 2014. He skipped the university in Hanoi to achieve BA in Amherst College in Massachusetts (US) and used to pursuit Master degree in Harvard Business University.

Former CEO of Uber Vietnam - Dang Viet Dung

In 2014, Viet Dung halted the study in Harvard  to return Vietnam and take charge of Uber leadership – a “rare” opportunity as he shared.
In Vietnam, Uber is offering services such as UberX, UberSUV, UberBLACK, uberMOTO, uber DELIVERY…  According to the statistic released on August,  Uber has four million users.
Mr Dang Viet Dung leaves Uber Vietnam at the time of hardship.
On Sep, 2017, it’s rumored that Uber Vietnam would be suspended due to tax problem. CEO Dung refuted the news. The company had to pay nearly $3 million in back-taxes and fines last month, but it is unclear if this had any bearing on the decision. Tax authorities in Ho Chi Minh City collected VND66.68 billion ($2.93 million) in arrears from Uber Vietnam, including fines for faulty declarations and late payments.
Recently, Grab and Uber Vietnam stumble the opposition from traditional taxi. When Ho Chi Minh city Transport Department requires Uber, Grab to stop connecting new transports, Hanoi Taxi Association files the petition to Vietnamese Prime Minister to end the pilot of Uber in Vietnam within September.