Panthers general manager Phil Gould announced on Monday that Lewis had been granted a release from his contract two years early with the NSW and Australia back-rower needing a new challenge away from the club where he'd spent 17 years, including his junior days.
"Luke has indicated he is at the stage of his career where he's feeling stale and as such is looking for a new outlook and challenge in his life," Gould said at Panthers headquarters.
"Luke feels as though he has given the Panthers all he can, but at this stage of his career he feels he needs a change of environment to achieve his goals."
Lewis, in his 11th senior season, was furious after Cleary handed the captaincy to Kevin Kingston after the opening State of Origin clash in May.
But the 28-year-old, who is the last remaining player at the club from the 2003 grand final-winning side, said the only reason for wanting to leave was to test himself at a new club.
Lewis also hosed down speculation he'd already had discussions with St George Illawarra and Cronulla for next season, saying no talks have taken place with any club.
"I need a whole new change of life with the way my head is at the moment but I have no idea what my next move will be," Lewis said.
"When the captaincy stuff happened, it was a bit of a hiccup that you get in football. It didn't really bother me I was over it a couple of days later."
Lewis revealed he made up his mind to leave during the recent State of Origin series.
"It probably hit me around game two of Origin," he said.
"But I wanted to focus on my football and my plan was when I got out of camp I would talk to my manager and the Penrith club and make sure there were no hard feelings.
"I'd never thought I would leave, but I think the best thing for me to do as a player and for the club is to move on."
Gould also denied Lewis's request was granted on the proviso that he did not sign with any of the club's western Sydney rivals.
"We've got no control over where Luke plays his football now," Gould said. "I've asked Luke and his manager to keep me abreast of the situation."