Mark Penn, who will become chief strategy officer, will get a bigger hand in determining which markets Microsoft should be in and where it should be making further investments, the New York Times reported, citing a person briefed on the change.
Penn was an executive vice president at Microsoft overseeing advertising and strategy.
Bates, the former Skype CEO in charge of Microsoft's business development, will leave immediately, technology news site Re/code reported on Sunday citing unnamed sources.
Eric Rudder, head of advanced strategy, will temporarily take up Bates' duties and marketing executive Chris Capossela will replace Reller, the report said.
Reller, one of the top female executives at the company and co-head of Microsoft's Windows unit, will remain with the company for some time to help with the transition.
The report said Nadella, who was appointed CEO on February 4, told staff of the changes on Friday and the company plans to announce them publicly on Tuesday.
© Thomson Reuters 2014