The former male model, 24, has played high school student and lacrosse team co-captain Jackson Whittemore since the show premiered in June 2011. When the show's second season ended in August 2012, Haynes' character had transitioned into a werewolf.
"Colton is leaving Teen Wolf," a source tells Us. "It's not that he didn't want to return because he did. It's that the heads of the show wanted to limit him to only appearing on half the season -- 12 episodes, not 24." Producers are also conducting a national casting search to find two identical male twins for season 3.
A spokesperson for the network denies Haynes will be exiting the supernatural smash, telling Us there is "absolutely no truth that Colton is being pushed out or that he, or any cast member, is being replaced. We love Colton and look forward to his returning with the entire cast for season 3 of Teen Wolf."
However, Haynes tweeted Thursday, "These past few yrs have been the best of my life. I'm sad that this chapter has ended, but excited for a new one to begin. Thanks for the love."
According to a source, the Teen Wolf cast is "devastated" by Haynes' sudden departure. "They are sad as they had become a family," the source tells Us. "Colton loves Tyler Hoechlin, Holland Roden and Tyler Posey. They are his best friends. He is upset that he won't be returning . . .He is being forced out of the show."
Though Haynes would have liked to continue playing Jackson Whittemore, "if he did the 12 episodes, he would not be able to work on anything else during the 12 episodes he's not on," the source says.