Veteran defender Barry Hunter has been named caretaker boss for the second time having been handed the reins before Tippett's appointment in April.
A club statement said: "Rushden and Diamonds Football Club has reached a mutual agreement with manager Ernie Tippett, and technical director Stewart Robson, that it is in the club's best interests for a change of management at this time.
"Jon Bolle, youth team coach, will also be relinquishing his responsibilities.
"The club would like to thank Ernie, Stewart and Jon for their efforts and wishes them well for the future."