DETROIT -- Travis Kalanick's combative personality created the culture that let Uber grow from startup to behemoth in just eight years. But under his direction the ride-hailing company had trouble growing up, leading to his downfall.

Kalanick, 40, stepped down late Tuesday, saying in a statement that his departure would help Uber return to growth "rather than be distracted by another fight."

This time the fight was with investors and his board, with several big players pushing for him to move aside. It was one fight too many after years of tussles with just about every business partner Uber touched.

"When you're at war with customers, employees, service suppliers, you can't build up a business model and Kalanick was at war with everyone," said Ferdinand Dudenhoeffer, director of the Center for Automotive Research at the University of Duisburg-Essen. "There is no business model in being at war."

App-based ride-hailing itself remains a topic of intense interest for the tech and auto industries as they compete to see whether Silicon Valley or the automakers will reap the profits from the digitalization of how people get from one place to another.

But "the significance of Uber has declined because the company has not managed to present itself in a stable and socially responsible way," Dudenhoeffer said.

Uber's board confirmed Kalanick's resignation early Wednesday, saying in a statement that Kalanick is taking time to heal from the death of his mother in a boating accident "while giving the company room to fully embrace this new chapter in Uber's history." He will remain on the Uber Technologies Inc. board.

The move comes as Uber, the world's largest ride-hailing company, struggles to morph from a free-wheeling startup into a mature company that can stanch losses and post consistent profits. After years of phenomenal growth at the expense of the taxi business, Uber had reached a point where the culture that created the company had become a liability that threatened to kill it.

It was unclear who would replace Kalanick.

Uber made a series of costly missteps under Kalanick that damaged its reputation, including revelations of sexual harassment in its offices, allegations of trade secrets theft and a federal investigation into efforts to mislead local government regulators.

Uber lost an expensive battle for supremacy in China against Didi Chuxing and had to be satisfied with taking a stake in Didi as a consolation prize. Uber posted a $708 million first-quarter loss, unable to turn $3.4 billion in revenue into a profit. The loss narrowed from $991 million in the previous quarter.

Investors have talked about selling stock in Uber to the public, a move that would imply a transition to an established business. The company was valued at near $70 billion the last time it sought capital.

On Tuesday, the company embarked on a 180-day program to change its image by allowing riders to give drivers tips through the Uber app, something Kalanick had resisted. Drivers have said that Kalanick didn't value their labour even though it was the heart of the San Francisco-based company.

Uber's board said in a statement that Kalanick had "always put Uber first."

But under Kalanick, the company developed a reputation for ruthless tactics that have occasionally outraged government regulators, drivers, riders and employees. The company often flouted city regulations for taxi companies with a culture that encouraged "Principled Confrontation."

The company's hard-charging style has led to legal trouble. The U.S. Justice Department is investigating Uber's past usage of phoney software designed to thwart local government regulators who wanted to check on whether Uber was carrying passengers without permission.

A key moment in Kalanick's fall came in February, when former Uber engineer Susan Fowler posted a personal essay about the year she spent at Uber, writing that she was propositioned by her manager on her first day with an engineering team. She reported the manager to human resources, but was told he would get a lecture and no further punishment because he was a "high performer," she wrote.

That caught the board's attention and brought outside investigations that led to the firing of 20 people including some managers. Former Attorney General Eric Holder conducted one of the probes, finding that the male-dominated Uber didn't have the most basic policies to protect workers from harassment. Holder's report suggested procedures that most companies have had for years such as using performance reviews to hold leaders accountable.

Also, Kalanick lost his temper in an argument with an Uber driver who was complaining about pay. The profanity-laced confrontation was caught on a video that surfaced in February. Afterward, Kalanick said he needed management help and had to grow up. The company began searching for a chief operating officer.

During the past year, several senior managers left the company, including the president and chief financial officer.

Kalanick said earlier this month he was taking an indefinite leave of absence, in part to deal with a personal tragedy. In May, his mother was killed and his father hurt in a boating accident on a California lake.

AP Business Writer David McHugh in Frankfurt, Germany, contributed to this report