Associate athletic director of communications David Bassity on Sunday said the decision to sever ties with CSC was made after seeing video of the Saturday night incident.
He said no decision has been made about possible legal action against the company.
Bassity said the school’s police department, which is investigating the incident, has spoken with the man who was hit.
Sports Illustrated reports there is at least one other video of a different incident allegedly showing a security guard assaulting a fan rushing the field.
CSC officials did not immediately respond to emails seeking comment.
CSC’s website says the company has provided crowd management to the Houston area since 1999.
The video went viral Sunday, racking up nearly 250,000 views by Sunday afternoon.