The team confirmed Monday that Barnwell was no longer on the roster.
The Nittany Lions are represented by nominees Ki-Jana Carter, D.J. Dozier, and Paul Posluszny.
Lane is the first safety and 17th player to join Penn State's recruiting Class of 2024.
Gilliam received offers from West Virginia, Virginia Tech, Indiana, and Texas A&M, among others, but chose the Nittany Lions after his official visit on June 2.
Plazz is the sixth offensive lineman of the Class of 2024.
The Nittany Lions will partake in "Big Noon Kickoff" games against Illinois and Michigan.