Uber's Chief Financial Officer has revealed he is stepping down from the online taxi service in an epic memo in which he says he is keeping a vow to spend more time with his wife and daughter. In the internal document, Brent Callinicos, 48, who joined Uber Technologies Inc in 2013 after serving as treasurer and chief accountant at Google, writes: 'For me, there is no later. It is now. 'It is time to do what I have desired for a very long time; time to keep a promise to my wife of not missing another school play, swim meet, or academic achievement of our daughter’s childhood.' The planned departure of Callinicos - who oversaw the company's fastest years of growth - was confirmed in an email by Uber's Chief Executive Travis Kalanick, which was sent out to investors. Scroll down for video . Family man: Uber's CFO Brent Callinicos (pictured) has revealed he is stepping down from the online taxi service in an epic memo in which he says he is keeping a vow to spend more time with his wife and daughter . A man of his word: Callinicos wrote that he had made a promise to his wife, Julie, not to miss another school play, swim meet, or academic achievement of their daughter, Alexi . Daddy's girl: Callinicos wrote that he wants his daughter, who is in middle school, to 'understand how important time is before time becomes a blur to her too' Successful: In the internal document, Brent Callinicos, 48, who joined Uber Technologies Inc (file picture) in 2013 after serving as treasurer and chief accountant at Google, writes: 'For me, there is no later. It is now' In the email, Kalanick said Guatam Gupta, 'Brent's right hand on Strategic Finance', will be the acting head of the company's finance division until a replacement is either found or named. Callinicos, who will stay on at Uber as an advisor and consultant, is the second financial head of a major Silicon Valley company in only a week to depart with a memo about prioritizing family. Last week, Google Chief Financial Officer Patrick Pichette announced in a Google+post that he was quitting his job to travel the world with his wife in what he described as a 'perfectly fine mid life crisis'. In Callinicos inspiring memo, seen by the Wall Street Journal, the CFO quoted philosopher John Dewey: 'Time and memory are true artists; they remold reality nearer to the heart’s desire.' He went on to explain how it is time for him 'to encapsulate what matters most to me', such as helping his daughter 'understand how important time is before time becomes a blur to her too'. 'After 26 years of nonstop work since MBA School, I am going to step back and spend some time with my family and let someone else take this amazing company to the next level as CFO,' he said. Executives: Callinicos's planned departure was confirmed in an email by Uber's CEO Travis Kalanick (left). Right, last week, Google CFO Patrick Pichette also left his job with a memo about prioritizing his family . 'My daughter is in middle school; my wife has been supportively waiting to spend time with me for 28 years. I made a promise to both of them that I would be taking a long break at this stage of life.' Callinicos thanked Uber and his talented colleagues, and said he was stunned by the company's success over the past two years. He added that he will be staying on as an advisor at the firm. '[I] will always be emotionally connected to this company. I will miss everyone here, but, like the rest of the world, I will watch and admire from the sidelines as I begin a new life with my family,' he said. Kalanick's email, which was seen by Reuters and Mashable, also referred to Callinicos's desire to spend more time with his family - and said the businessman had done a 'wonderful' job at the firm. Rise to popularity: Uber, which is valued at around $41billion (compared to the $3.5 billion it was valued at when Callinicos joined the firm in 2013), is now available in more than 53 countries and 200 cities worldwide . 'Brent has done a wonderful job here at Uber but has decided that it is time for his next journey, one where his wife and daughter take the front seat,' the 38-year-old CEO wrote in the email. He added that Uber was around '1/10th' of the size it is today when Callinicos joined the company. Callinicos, who lives in California's San Francisco Bay Area with his family, is one of the highest ranked executives to leave Uber. He also previously worked for The Walt Disney Company. Gupta, who will be acting head of finance, is a former Goldman Sachs Group Inc vice president. Uber, which is valued at around $41billion (compared to the  $3.5 billion it was valued at when Callinicos joined the firm), is now  available in  more than 53 countries and 200 cities worldwide.
Brent Callinicos, ex-Google chief accountant, joined Uber two years ago . Oversaw the firm's fastest years of growth; it is now valued at $41billion . In internal memo, he revealed he is departing after making a vow to wife . 'It is time to do what I have desired for a very long time,' said Callinicos . He said he wants to attend his daughter's school plays and swim meets . Uber's Chief Executive Travis Kalanick confirmed departure in an email . Replacement for Callinicos is yet to be announced by online taxi service .