"Pat has been a tremendous asset to this team over the past three years, Pat's appointment was the start of a major restructuring exercise, and he has been pivotal in reshaping Williams into what is a much stronger racing team today," Williams deputy team principal Claire Williams told Sky Sports.
Symonds is expected to be retiring, with Paddy Lowe set to move over from Mercedes to take his place, although Williams was not willing to discuss Lowe's arrival.
"I would like to thank him (Symonds) for all of his hard work and commitment during that time. We now look to the future and will be announcing details regarding the team's technical leadership in due course."
Bahrain International Circuit - Winter testing