Microsoft Corp said on Monday that chief software architect Ray Ozzie, the man who took over that role from co-founder Bill Gates, would retire and not be replaced.

The move signals a new phase in Microsoft’s shift toward cloud computing, which Ozzie championed, and cements control of the company’s direction under Chief Executive Steve Ballmer.

Ozzie, 54, who created the groundbreaking Lotus Notes email system early in his career, took on the role of overseeing Microsoft’s software direction in 2006.

He had made a splash at the company the year before, shortly after he joined, with his now-famous “Internet Services Disruption” memo, which pushed Microsoft strongly in the direction of the Internet and cloud computing, the provision of services and data over the Internet.

Some saw that as a challenge to Microsoft’s core business of getting software installed on as many computers as possible, but the company now says it is “all in” for cloud computing.

Microsoft shares fell 2.2 percent to $25.25 in after-hours trading.

According to a memo sent by Ballmer on Monday, Ozzie will quit his post to focus on entertainment efforts at the company and retire after an unspecified time. The company said it would not refill the chief software architect role.