Fernando Salgado, 18, originally pleaded guilty as part of a plea deal. He was released from jail in exchange for testifying against his teacher.
A judge is expected to decide on his plea at a hearing Sept. 6. Salgado was sentenced to 180 days in jail to be served on weekends.
Prosecutors say the teacher, 27-year-old Emmanuel de la Rosa, directed four students at A.B. Miller High School to assault two classmates. De la Rosa has pleaded not guilty and remains free on bail.