In a statement issued Sunday, the Kings said Hardy resigned on Friday.
Hardy's attorney says the former NHL defenseman has entered an alcohol treatment program.
Hardy was arrested last month in Washington, D.C., after a woman said he fondled her in a hotel room after a night of heavy drinking. He is scheduled to return to court July 1.
The 51-year-old Hardy had spent 21 years with the Kings as a player and a coach. After seven seasons in the Chicago Blackhawks' organization, he returned to Los Angeles in August 2008 to join Terry Murray's staff.