Shashank's removal is the only solution for smooth conduct of the November 28 Assembly elections, the chief minister said in his letter.
Chuaungo, a 1987-batch Gujarat-cadre IAS officer, has been relieved of his responsibilities in the state.
The EC has instructed him to report before the Ministry of Home Affairs in Delhi.
"The only solution for smooth conduct of Assembly elections 2018 now would be removal of CEO S B Shashank from office forthwith," the chief minister wrote in the letter, a copy of which is available with PTI.
"Additional CEO can take over Shashank's responsibilities if making fresh arrangements were difficult at this juncture," the chief minister said.
Earlier in the day, the CEO told reporters here that he was fulfilling his responsibilities in accordance with the poll panel's instructions, amid growing demand for his ouster by the civil societies.
He also said he had "no intention to hurt the sentiments" of the state's civil societies and apologised for rankling them.
Talking about his fallout with Chuaungo, the CEO said he had issued a statement to the District Election Officers (DEO) and Electoral Registration Officers (ERO) on September 11 to notify that "identification slips could be used as valid documents by eligible Bru migrants in Tripura".
Chuaungo, however, issued another order on September 13, asking the Bru refugees to refrain from using the identification slips, except for the purpose of repatriation, he said.
"As the state chief electoral officer, it is my duty to intimate the EC about the developments. I can only hope that the civil societies will understand my position. I am sorry if I have hurt anybody," he told reporters.
NGO Coordination Committee, an umbrella body of major civil societies and student organisations, has sought Shashank's exit at the earliest and issued a statement to say it would picket the state election office from Tuesday.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)