Not exactly. He decided to step down on his own.
One day he called Iwata to his office and started talking to him about business and the industry in general. It was a very long talk.
Iwata initially thought Yamauchi was firing him. But it was actually to give him his position because he thought Iwata was good enough for such a position.
Yamauchi's authority knew no limits. No one could tell him what to do. Absolutely no one. All of those who even dared to do that got thrown away.