Assistant John Stevens was appointed head coach and former Flyers coach Paul Holmgren was promoted from assistant general manager to interim general manager - the latest combination in an attempt to end a 31-year Stanley Cup drought.
The Flyers are 1-6-1 and have the fewest points in the NHL.
"The decisions that had to be made, I was letting other people make them," said Clarke, acknowledging he was burned out. "I deeply regret not being able to bring a Stanley Cup here. I didn't deliver."
Flyers chairman Ed Snider said he decided to fire Hitchcock after an embarrassing 9-1 loss to Buffalo last week, one of the worst in the franchise's 40-year history.
"We don't expect miracles, but we're hoping for a lot better results," Snider said.
Hitchcock, in his fourth year with the Flyers, said he would've liked a chance to turn the season around.
"I'm disappointed we weren't able to bring in the Cup," he said. "It's disappointing, personally, I wasn't given the opportunity to turn it around."
Clarke said the Flyers' record played no role in his resignation. He said he began feeling spent during last year's draft and hoped for a renewed passion once the season started. That never happened, and Clarke said he decided to quit after the third game of the season.
"I just don't have the desire to do what this job requires," Clarke said. "I was tired of doing it."
Stevens will be behind the bench when the Flyers play at home Thursday against Atlanta.
"I don't think we tuned him out. I think Hitch is a good coach, but sometimes you need a change," Flyers captain Peter Forsberg said.
As general manager, Clarke never matched the success he had as a Hall of Fame player when he led the Flyers to Stanley Cup championships in the 1973-74 and 1974-75 seasons. Clarke was in his 13th season in his second stint as general manager, after handling the GM role in the 1980s.
Hitchcock signed a three-year contract though the 2008-09 season in training camp. He led the Flyers to the conference final in 2004, where they lost to the Tampa Bay Lightning, who later won the Stanley Cup.
Before Hitchcock was hired, the Flyers used five coaches in the previous six seasons.
"He realized that we had to make a change, and he's behind the organization and he's willing to do whatever he can to help the organization move forward," Snider said.
In 10 NHL seasons with Dallas and Philadelphia, Hitchcock is 408-249-100. He is 66-51 in playoff games and won the Stanley Cup with Dallas in 1999.
This is Philadelphia's worst start since another 1-6-1 start in the 1989-90 season. The Flyers missed the playoffs that season, starting a five-year span without a post-season appearance.
The Flyers have scored only 15 goals in eight games - five by Simon Gagne. They are a woeful 4-for-55 on power-play chances this season.
"We're all responsible for what happened," Gagne said. "It's not only them. It's enough. We need to find a way."
Philadelphia was bounced in the first round of the playoffs by Buffalo last season, and has seemed ill-equipped to win a Stanley Cup in a changed NHL where speed and scoring are more valuable than the big, tough guys they've traditionally built around. Many of the same problems they had last season have lingered, notably a plodding defence that has yet to score a goal.
The Flyers waived three players last week after the blowout loss to the Sabres, including Nolan Baumgartner, their lone free-agent signing to bolster the defence.
With a shaky defence and little offensive punch, the goaltenders have struggled, especially opening night starter Robert Esche. He has allowed 13 goals in two winless starts.
Known for his "toothless grin," Clarke played for the Flyers from 1969-84 and captained the famed "Broad Street Bullies" teams in the 1970s. He immediately went from playing into management, holding the GM role from 1984-90. He returned to the position in 1994, famously feuding with Eric Lindros in 2000.
"I don't know what happened. I don't know why it happened," Clarke said. "I would have never thought I'd get tired or burnt out or something. But this is what's happened. I've got to try and figure out why and how."
Hitchcock also led Dallas to two Stanley Cup finals appearances - winning the title in 1999 and going back the next year - and five straight division titles.
Stevens was the coach for the Philadelphia Phantoms, the Flyers' AHL affiliate, from 2000-06 and led them to the Calder Cup championship in 2005. Stevens was Philadelphia's third-round pick by the Flyers in 1984 and played 53 games with the Flyers and Hartford Whalers.
"We're very confident we can turn this thing around," Stevens said.