The departure comes after the Ladies lost 5-1 at Watford in the FA Cup third round and after a largely frustrating season which has seen the Hammers win just three games out of 12 in the FA Women's Premier League South.
A club statement, released earlier this morning, read: "Today we announce with regret that the First Team Manager, Mark Saunderson has left the club with immediate effect.
"Today we have an important County Cup Match and Steve Spence with the support of Julia Setford we be in charge."
The Ladies play their home games at Thurrock FC, Ship Lane, Grays, Essex, RM19 1YN. For more information about the Ladies and their upcoming games click here
By David Blackmore