The 43-year-old, who joined the Woking team in 2012, is expected to return to his native Australia with his family.
Michael began his 21-year Grand Prix career with Team Lotus in 1993 before joining Jordan Grand Prix in 1995, where he established the team’s R&D group before progressing into a senior race engineering role.
He joined Williams as chief operations engineer in 2001, progressing to the position of technical director in 2004, a role he held until the end of 2011.