Microsoft’s Chief Executive Officer Satya Nadella on Thursday announced that Terry Myerson, the head of the firm’s Windows and Devices Group, had decided to leave the company. Myerson was instrumental in transforming Windows by creating a secure, modern operating system.

“His strong contributions to Microsoft over 21 years from leading Exchange to leading Windows 10 leave a real legacy,” Nadella told employees in an internal email. “I want to thank Terry for his leadership on my team and across Microsoft. He will work with me on the transition over the coming months.”

The company has also decided to split up its Windows engineering team, and with Myerson’s departure, the Windows era in Microsoft will come to an end. The moves, analysts told The New York Times, were part of a decision to accelerate Microsoft’s emphasis on faster-growing businesses such as cloud computing and artificial intelligence.

In his email, Nadella also mentioned the important role of cloud computing to the company’s future and the advances in artificial intelligence that have the potential to improve the company’s products. The organisational overhaul “enables us to step up to this opportunity”, he added.

Microsoft is competing with leading cloud provider Amazon Web Services, and the shift in focus is highlighted by the fact that the three top Windows engineers will now report to Jason Zander, who heads the Azure cloud computing platform, Financial Times reported. Developers who used to work on the Windows operating system will now join Microsoft’s “cloud and AI” group, which will oversee all the company’s software platforms from Azure to its software for the Internet of Things.

Although Azure is still a far smaller business than Windows, its revenues increased 98% in the last quarter.