University of Missouri system president Tim Wolfe resigned Mondayafter football players and professors joined protests against his handling of race-related issues on campus. “I take full responsibility for this frustration,” Wolfe said. More than 30 football players announcedSaturday they would boycott practices and games until Wolfe resigned or was terminated. A faculty group had called for a walkout Mondayand Tuesday. Chancellor R. Bowen Loftin, head of the system’s flagship campus, also announced he would step down.