
The former Liverpool midfielder, who had been assistant coach, took charge in the summer when Sam Allardyce moved to Newcastle, but nine league games brought just one victory.
Matters came to a head following a falling-out with assistant coach Gary Speed.
"This has been a difficult decision for all parties but we have agreed that time is right," said chairman Phil Gartside.
"Sammy has played an important role in the Club's recent history. We wish Sammy and Frank well for the future." dpa