Harrop, who was appointed in May 2022, had to work within what is thought to be one of the smallest budgets in the top tier of English non-league football.
He gave assurances to the board about steps he was planning to bring spending under control, but it did not happen to their satisfaction.
Harding said the manager hoped money from an FA Cup run would improve the situation, but they were beaten on penalties by Brackley Town of National League North in the first round.
“You can’t budget for success in the FA Cup. If it happens, it’s a windfall,” he continued.
“The situation got to a point that when we had a chat about it at a board meeting, and had the situation continued for any further time, we’d probably have found ourselves in administration in the new year, it was that serious for us.
“We were spending significantly more than we could afford, so we had to make a difficult decision. The disappointing thing is that Angelo is a good coach, has achieved much for us and we are grateful for all the success.
“But the board’s overriding consideration is to make sure we’re here next year.”
Goalkeeper coach Justin Moseley is in interim charge of the team, who play West Brom Under-21s in the National League Cup on Tuesday.
Meanwhile, Harding said he was receiving 15 or 20 calls a day and numerous emails about the vacant job.
In a statement to BBC Essex, Harrop said: “There needs to be structure at the club. I’ve been pushing that for a long time. Braintree don’t have Under-18s, Under-23s, that’s a big worry for the club.
“We have to be realistic. Braintree has one of the smallest budgets in the league by a country mile. I tried to move players (out) but they were under contract.
“Running the club and the team, it’s a big ask.”
Listen to the full BBC Essex interview with Lee Harding from 18:30 on Tuesday
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