Lynn Swann is OUT at USC ... the ex-NFL superstar just resigned his post, according to school officials.
67-year-old Swann took the job back in April 2016 -- replacing longtime AD, Pat Haden.
No word as to why Swann is resigning.
USC President Carol Folt sent an email saying, "Lynn has been a leader on and off the field at USC for nearly five decades, and he will forever be a valued member of the Trojan family."
Swann has been under fire in his role as AD basically since he took the job.