"I wish Andrea luck, I am sure he will continue what I have started and show that people from our country are honest and hard-working...," Cellino said in a statement on the club's website (www.leedsunited.com).
"Owners come and go but Leeds United will be there forever. Goodbye and farewell."
The Yorkshire side are one of England's traditional soccer giants, having won the top-flight title three times.
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But they lost their Premier League status in 2004 and have undergone turbulent times under Cellino.
The Italian was banned by the Football League and FA, which applied the latest sanction last December when he was ordered out of the game for 18 months and fined 250,000 pounds ($324,175.00) for breaching agent rules over the sale of a player.
One month later he sold Radrizzani an opening 50 percent stake in the club, who finished seventh this season, just outside the playoff places.
Radrizzani becomes club chairman with immediate effect.
(Reporting by Neil Robinson; Editing by Ken Ferris)
