Uber CEO Travis Kalanick made the announcement to staff via email on Tuesday (11 April), saying Whetstone was "a force of nature, an extraordinary talent and an amazing player-coach", and suggested she would still advise the business.
In the email, seen by PRWeek, Kalanick said: "Rachel was way ahead of the game when it came to many of the changes we needed to make as a company to ensure our future success - from promoting cross-functional teamwork to improving diversity and inclusion."
He also announced Uber global policy and comms senior vice president Jill Hazelbaker as Whetstone's replacement, though it is unclear whether this is an interim appointment.
Before joining Uber in 2015, Whetstone handled comms and public policy at Google for 10 years, her LinkedIn profile states. She was also the first employee of the comms agency Portland, when founder Tim Allan hired her from the UK's Carlton TV. Her boss at Carlton had been David Cameron, who would later become UK Prime Minister.
A statement from Whetstone supplied to PRWeek by Uber said: "I am incredibly proud of the team that we've built - and that just as when I left Google - a strong and brilliant woman will be taking my place."
There are not expected to be any changes to the EMEA and UK & Ireland comms teams as a result of her standing down, PRWeek UK understands.
In recent months the ride-hailing service has suffered a series of reputational blows, including a legal battle with drivers in the UK, public protests around the world, and allegations of sexual harrasment against staff members.
A video (below) also emerged in February of Kalanick losing his temper with a driver who said he had gone bankrupt as a result of the company’s practices.
Speaking to PRWeek UK editor-in-chief Danny Rogers in March, PR legend Matthew Freud said the issues Uber faced were "probably a fairly accurate reflection of the company's values".