"I may have behaved inappropriately and that certainly has played a part in my decision-making," Newton said.
"If I have done any wrong anywhere, I certainly take full responsibility for that."
He said he enjoyed his time with the council and praised fellow councillors for their work.
"I tried to do my damnedest for the Waihemo community and get things moving down this way, and I'm certainly thankful for the support of the community during my election and tenure.
"I'm looking forward to taking some time out for my family ... and being a better dad."
Waitaki Mayor Gary Kircher declined to comment on the allegations, but said he had not received any formal complaints and did not believe any had been laid with the council's chief executive, Fergus Power.
Power did not return requests for comment yesterday.
A by-election will be held in the new year.
Newton was the sole councillor for the Waihemo ward.
A "buddy councillor" would be appointed to work with the Waihemo Community Board in the interim.
"We want to make sure there isn't a gap as such and making sure we are looking after the good people of Waihemo," Kircher said.
Newton was elected in 2019, beating incumbent Jan Wheeler by 79 votes.
Wheeler said she had not decided whether to stand in the by-election.