KARIM MAYFIELD ANNOUNCES HIS RELEASE FROM MANAGERIAL CONTRACT March 10, 2010 San Francisco, CA – Boxing’s undefeated welterweight sensation, Karim “Hard Hitta” Mayfield (11-0-1, 7 KO’s), is now a free agent after his managerial contract with Jackie Kallen has concluded. Mayfield, a rising star from San Francisco, is looking to explore his options with other…