The 54-year-old will end his 10-year reign in charge at Wantage Road with the LV= Insurance County Championship fixture at Essex in a couple of weeks' time, before switching to different coaching role at the club.
And that is something Warren feels is crucial, saying 'you don't let good people go'.
Ripley has been head coach throughout Warren's time as chairman of the club, a spell in which he delivered two T20 Blast titles, and two promotions from County Championship Division Two.
And, as Warren revealed he has at times had to work under difficult financial conditions.
"Part of the reason I have the utmost respect for Rips is because, when I came in as chairman, the financial situation meant I cut his budget by 33 per cent," Warren told BBC Northampton.
"It wasn't an easy decision to make, but it was a case of having to, and Rips said 'fair enough chairman, I understand what you are doing, I understand the strategy and we will get on with doing what we are doing'.
"We trusted each other, and he then delivers the 2013 T20 trophy, along with promotion, makes the final in 2015 and then wins it again in 2016.
"I think he is the club's most successful coach, and that is why you don't let good people go."
News of Ripley's decision started filtering through on Tuesday night after it was announced at the club's AGM, before being officially confirmed on Wednesday morning.
Ripley told the players before the ongoing Championship match against Surrey started on Sunday, and Warren felt it was crucial the time of the announcement was handled properly.
"The announcement was firstly made to the players on Sunday," said the chairman.
"Talks have been ongoing for many weeks, but it was key that Rips was in charge of the narrative and we dealt with it in the right way
"He has said that now he has announced it he is almost relieved, and hopefully he can enjoy a victory against Surrey today, and then we have our last couple of fixtures against Durham and Essex."