"I've also helped American lightweight double sculls which tried to qualify [in 2012] and Michelle Guerette who went on to an Olympic silver [at Beijing].
When asked whether there had been any fallout with Rowing New Zealand, Tonks said: "We're finished. I'm finished with New Zealand rowing."
His last day was Sunday.
However, a final decision is expected by lunchtime with Rowing NZ chief executive Simon Peterson saying they are hopeful Tonks will still coach his two crews to Rio.
"We have always wanted him to coach Olympic champion Mahe Drysdale and the women's double [current world champions Zoe Stevenson and Eve Macfarlane]. That's the agreement we had, and it hasn't changed in our view."
Drysdale told Radio Sport he was yet to hear of any final decision.
"I certainly haven't been told. Personally, I hope my relationship hasn't ended [with Tonks] whatever the case may be with Rowing New Zealand. That would be very sad but I guess we'll find out soon.
"My preference is that he takes me to the Olympics, that's in my plan and what I'm working on until that changes. There's a process going on, I hope it works out for everyone. The women's double and I don't want to change anything eight months out from the Olympics."
The relationship between Tonks and Rowing NZ has faced strains before, like when he stepped down from his role of head coach to lead the women's programme in 2013.
The 64-year-old has a reputation for being a hard task-master but is the most successful coach in New Zealand Olympic history, mentoring Rob Waddell, Georgina Earl and Caroline Meyer [nee Evers-Swindell], Drysdale, Hamish Bond and Eric Murray to the top of the podium.
Tonks is a five-time Halberg coach of the year winner (1999, 04, 05, 09, 12).