The manager's brief tenure came to an end after he and the club "reflected on events both on and off the field," according to sporting and technical director Richard Garlick.
West Brom has parted with head coach Pepe Mel by mutual consent.
Sporting and technical director Richard Garlick said: "We would like to thank Pepe for his efforts over the past four months in helping to keep the club in the Premier League and wish him well for the future.
"Both Pepe and the club set out with the best intentions of making the appointment work. However, having reflected on events both on and off the field during our talks today, it became apparent that it was in the best interests of both parties for there to be an amicable parting.
"We are grateful for the manner in which the existing coaching staff and players have rallied behind Pepe to get the club over the line in what has proved an extremely competitive division."