Microsoft Corp said on Thursday Steve Luczo stepped down from its board of directors so he can focus on his job as chief executive of digital storage company Seagate Technology Plc. Luczos exit comes just six weeks after the appointment of Satya Nadella as Microsoft chief executive, which Luczo played a key role in as a member of the software companys four-man search committee. Luczo, 57, had been a member of Microsofts board since May 2012.