After initially side-stepping questions about his future, Chieka stayed true to his stance that he would end his five-year tenure with Australia if they failed to win the World Cup.
"I got asked the question in the press conference, you would've been there and listening, about what's going to happen going forward and at the time I wasn't keen to answer but I always knew the answer in my head, I just wanted to speak to my wife and tell a few people up there about it," Cheika told rugby.com.au.
"I put my chips in earlier in the year I told people no win, no play.
"So, I'm the type of man who always going to back what he says and I knew from the final whistle but I just wanted to give it that little bit time to cool down, talk to my people and then make it clear."
Cheika has had a rocky relationship with the country's rugby administration, having been subject to a review this time last year after a poor 2018 season which resulted in the sacking of attack coach Stephen Larkham.
The review also brought on the appointment of Scott Johnson and Michael O'Connor as Wallabies selectors alongside Cheika, something that didn't sit well with the 52-year-old coach.
The departing Cheika saved one parting shot for Castle and the Rugby Australia administration.
"It's no secret I've pretty much got no relationship with the CEO and not much with the chairman," he said.
"Scott's a lovely bloke and I get on fine with him but I'm not really into that type of thing, I like to take that responsibility.
"I found also that it changed my normal routine around things.
"Not that my way's definitely the right way, I'm definitely not saying that but that's just the way I like to operate.
"I've always prided myself on not compromising my own values and what I want to do so I found that a little bit difficult at times.
"It's tough because you're sort of betwixt and between, you so want to be a part of it and then sometimes it can't always be how you wanted but that's the way the role's set up and I know my place within that structure.
"So you either follow it, which I've tried to do over this last 12 months or you make the choice not to be in it."
Castle thanked the "passionate" Cheika for his service to the Wallabies and said there will be a "thorough review" of the side's 2019 season.
"On behalf of Rugby Australia, I want to thank Michael for his dedication and service to the role of Wallabies Head Coach since taking up the position in 2014," she said in the statement.
"Michael is a passionate and experienced coach who worked tirelessly to get the best out his players. He cares deeply about the Wallabies and the game of Rugby, and always set out with the aim of making Wallabies fans proud of the team's performances.
"Michael came into the role at a turbulent time, and experienced immediate success by taking the Wallabies to a World Cup Final after only one year in the job. He was later given the ultimate recognition for that achievement by being named World Rugby Coach of the Year.
"Now that the Wallabies have exited the tournament, Rugby Australia's Director of Rugby, Scott Johnson will lead a thorough review of the Rugby World Cup campaign and the 2019 season.
"This is an important process which is undertaken at the completion of each tournament or series and this review will examine all aspects of the Wallabies program, from coaching to physical preparation, player fitness, and skill development.
"As expected at the end of a Rugby World Cup year, there are a handful of senior players leaving the Wallabies program and coaching staff coming off contract ahead of next year. There has already been much work completed in preparing for the future in this regard, and that work will also continue until the end of the year."
Cheika did admit that he would have liked to stay on but said he was committed to his word that he would leave if he failed to lead his side to a World Cup triumph.
"I had no regrets about making the call but yes I would love to stay on," he said.
"I'm really attached to the team and it's an honour doing this role, coach of Australia.
"It's not given to a lot of people and I take it with a lot of pride and a lot of honour but like I said I made my call and I wanted to show that I prepared to put myself on the line to achieve what I believed the team could. We didn't do that and I've got to stand by what I said."
Cheika's stint as Wallabies coach began with a run to the World Cup final in 2015, but has struggled since managing just 23 wins from 51 tests.