Clark is best known for making "The Catch" while a player with the San Francisco 49ers. He had been with the Browns since 1999, when they returned to the NFL as an expansion team.
Browns president Carmen Policy, in Houston at the NFL meetings, said Clark left the Browns to pursue other goals in football, not because he lost a power struggle with Cleveland second-year coach Butch Davis.
"You'd have to consider this a joint decision," Policy said. "He wants to try something else."
Clark oversaw the Browns draft choices during his three years with the team. Several players Clark selected have become building blocks for the team's future, including starting quarterback Tim Couch.
Couch was surprised to hear of Clark's departure.
"I'm sad to see him go," Couch said at a Browns banquet Monday night. "He drafted me, he brought me here and he made me a Cleveland Brown. I am forever grateful to him for what he did for me."
Policy said that after working with Davis through last season and this year's draft, Clark "acknowledged this coach's ability and said 'Look, I'm not going to let my ego get in the way.' "
He said one of Clarks strengths is that "when he sees what you can do, and he realizes that you're better than him at doing some of the things that he may have the ultimate responsibility to do, he's going to do what's best for the team."
Clark declined to comment.
With Clark's departure, Davis takes full control of the Browns roster, though his title will not change, Policy said.
"We're going to have the coach giving the greatest degree of input as to where we're going and who we're selecting when it comes to pro personnel," Policy said.
Davis said Monday he had a good working relationship with Clark.
"We always had a good dialogue and a nice exchange of ideas," Davis said. "I assumed we would be working together again during the 2002 season, so I was surprised and disappointed to learn that he is leaving."
Policy said Clark would not be replaced and neither would Keith Kidd, the Browns pro personnel director since 1999, who also has left.
Clark, 44, joined the Browns in November 1999 after spending 19 seasons with the 49ers, nine as a player. He was a member of five Super Bowl winners with San Francisco and is best remembered for catching Joe Montana's TD pass in the 1981 NFC Championship Game to beat the Dallas Cowboys.
Clark had been brought to Cleveland by Policy, whom he worked with in San Francisco.
Clark had control of the Browns' football operations for two years before Davis replaced Chris Palmer as Cleveland's coach before last season.
The Browns had a combined record of 5-27 over their first two seasons, leading some critics to call for the ouster of both Clark and Palmer.
Clark stayed on. But when Davis brought in Pete Garcia, his assistant with the Miami Hurricanes, to help with player development, it appeared Clark was the odd-man out.
Policy said Clark deserves credit for helping to guide the Browns through the difficulty of the 1999 expansion draft and for helping to build the foundation for the team to compete for the playoffs this year.