Volatile club president Maurizio Zamparini had also said in September that he envisaged Mangia staying for years and emulating Arsene Wenger, who has been manager of English Premier League Arsenal since 1996.
"Palermo communicates that coach Devis Mangia and his staff have been relieved of their duties with the first team," said the club in a statement, one day after losing 2-0 to Sicilian rivals Catania.
Mangia, in charge since August, became the fourth coach to be dispensed with by Zamparini this year, with Delio Rossi, now at Fiorentina, losing his job on two occasions.
Zamparini fired Rossi earlier this year after a 7-0 home defeat by Udinese and also dismissed his replacement Serse Cosmi one month later.
Rossi was then rehired but left at the end of last season by mutual consent. Stefano Poli was appointed in his place but was also sacked at the end of August following elimination in the Europa League qualifiers by Swiss side FC Thun.
Mangia, who has coached teams in the lower division, was promoted from youth team coach to replace him, initially as caretaker.
In September, Zamparini said: "I'm prepared to give Mangia 100 percent credit and want to take a gamble on him, I think he's a coach who can do great things, I don't want to lose him and I want to begin a new cycle with him."
Palermo are tenth in Serie A with 20 points from 15 games. They have won six out of seven homes games but have failed to score in eight attempts away from home.
