Gamecocks head Coach Steve Spurrier said the quarterbacks coach is off duty until further notice.
"G.A. has been suspended from all coaching activities until this matter is resolved," Spurrier said. "We are disappointed in his actions and will handle it accordingly."
Greenville, S.C., Police allege Mangus was urinating in public Monday when he was questioned by an officer in an unmarked car, The (Columbia, S.C.) State reported.
Police said Mangus, who joined South Carolina in 2009, was uncooperative and evasive and displayed slurred speech when confronted.
"Last night I acted irresponsibly and I deeply regret my actions," Mangus said in a statement. "I take full responsibility. I would like to publicly apologize to Coach Spurrier, Eric Hyman, the entire team, and everyone associated with the University of South Carolina."