"Unfortunately, he will soon be fired," club president.Jacky Lorenzetti told rugby weekly Midi Olympique.
AAP reports the 35-year-old Williams was charged last month.
Former Wallabies winger James O'Connor, who plays for Toulon, was also arrested and charged with possession.
Both players have been stood down by their clubs.
Williams, a 77 test veteran, has been summoned to appear at the National Rugby League's discipline commission on 29 March.
He is alleged to have purchased $300 worth of cocaine.