Twenty-one years after founding Google in a messy garage in Menlo Park, California, Larry Page and Sergey Brin have stepped down from day-to-day management of the company to assume the role of “proud parents – offering advice and love, but not daily nagging!”

Page and Brin’s decision to hand over control of Google, and its parent company Alphabet, to long-standing lieutenant Sundar Pichai is the end of an era for the search engine giant, which had been built in their image and followed their personal values.

Their exit from the executive suite is the biggest change at the top of a US technology powerhouse since Steve Jobs resigned as chief executive of Apple shortly before he died from cancer in 2011, or when Bill Gates, the billionaire founder of Microsoft, stood down as chief executive in 2000. Amazon’s Jeff Bezos is now the only founder-chief executive from that period to still be in day-to-day control of his company.

“Today, in 2019, if the company was a person, it would be a young adult of 21 and it would be time to leave the roost,” Google’s founders wrote in a public letter on Tuesday. “While it has been a tremendous privilege to be deeply involved in the day-to-day management of the company for so long, we believe it’s time to assume the role of proud parents – offering advice and love, but not daily nagging!

“We’ve never been ones to hold on to management roles when we think there’s a better way to run the company. And Alphabet and Google no longer need two CEOs and a president.”

Pichai, 47, who was previously chief executive of Google, will take on all of those roles as Alphabet’s chief executive. He owns about 0.1% of Alphabet’s shares.

“I’m excited about Alphabet’s long-term focus on tackling big challenges through technology,” Pichai, who has worked at the company since 2004, said on Twitter. “Thanks to Larry & Sergey, we have a timeless mission, enduring values and a culture of collaboration & exploration – a strong foundation we’ll continue to build on.”

Brin and Page, both 46, said they would remain “actively involved” as board members and major shareholders. “In addition, we plan to continue talking with Sundar regularly, especially on topics we’re passionate about,” they said.

Page had been chief executive of Alphabet since the parent company was created in 2015 to manage all of Google’s disparate “moonshoot” ventures, including flying cars and technology to disrupt the ageing process.

Brin had been president of Alphabet and had already distanced himself from day-to-day management. For a time, Brin had moved his desk to X, the self-described “moonshot factory” where engineers worked on projects that were expected to fail but had big potential if they didn’t.

Together, Brin and Page control 51% of a special class of Alphabet’s voting shares, giving them ultimate control of the company’s future direction. They own 11.4% of the company, worth $101bn (£77bn). Alphabet’s total stock market value is $912bn and has increased by almost 25% so far this year.

Page and Brin are ranked the seventh- and tenth-richest people in the world, according to Bloomberg Billionaires Index with estimated fortunes of $62.7bn and $60.9bn respectively.

Under Page and Brin, Google’s motto had been: “Don’t be evil” but it was changed to: “Do the right thing” when Alphabet was created in 2015.

The company has recently faced a growing number of complaints and allegations from politicians and its own workforce. Last year Page was called before the US Senate Intelligence Committee investigating foreign powers’ influence in elections, but he didn’t show up.

Last week, Google dismissed several outspoken workers for allegedly violating its data security policies. Some employees accused the firm of trying to suppress its critics.

Thousands of employees walked out of Google offices around the world last year to protest against a $90m payoff to the former Android boss Andy Rubin, despite finding sexual misconduct claims against him to be credible. The board has since opened an investigation into how executives handle claims of sexual misconduct.

Employees also protested against the company’s contract with the US Department of Defence for artificial intelligence work, arguing that Google should not be in the “business of war”. Google said last year it would not renew the contract.

Google was fined €1.5bn (£1.3bn) by the European commission earlier this year for “abusive practices” in its AdSense platform by blocking rivals Microsoft and Yahoo from selling ads in Google search results pages. This followed a $5bn fine for anti-competitive behaviour associated with its Android mobile operating system in 2018 and a €2.4bn fine for ecommerce violations in 2017.

The pair’s reference to becoming “proud parents” is a knowing nod to the “parental supervision” they brought to the company when they appointed the Silicon Valley veteran Eric Schmidt as Google’s chief executive in 2001, when Page and Brin were still in their 20s and the company was growing rapidly.