Downey Jr. made the confirmation via his twitter page on Monday, December 24, 2018.
Further confirming the exit of the popular character played by Downey, Captain America star, Chris Evans revealed that he, Downey, and Chris Hemsworth will exit the Marvel Cinematic Universe contractually after the release of the fourth Avengers movie, 'Avengers: Endgame.'
“Myself, Downey, Hemsworth, we all kind of started roughly at the same time, and I think we all, through Avengers 4, kind of wrap it up,” Evans said. “So at this point, I don’t know what’s next, but yeah, by 2019, that’s it,” he told comic book.
'Avengers: Endgame' directed by Anthony Russo and Joe Russo is scheduled for April 26, 2019 in the United States of America