The official, hailing from Bhubaneswar, cited personal reasons for taking the decision.
"It is very personal (reasons). My family is at Bhubaneswar. I want to spend more time with them," he told a news channel.
Meanwhile, confirming the development, a top government official said Mohapatra cited personal reasons for the decision and had already put in his papers.
"I got information that company has already got a person in his (Mohapatra) place," the official told PTI on condition of anonymity.
The construction agreement for the Rs 7,525 crore Vizhinjam International Deepwater Multipurpose Seaport project was signed between Adani Group Chairman, Gautam Adani and then Kerala Chief Minister Oommen Chandy, on August 17, 2015.