Brown was a sixth round pick in the 2020 NFL Draft.
Souliere appeared in 85 games over his four years with the Nittany Lions.
The commencement for the college will kick off at 1 p.m. on Saturday, May 4.
The forward will join the Sun Devils for his senior season.
Guðmundsson leaves with three years of eligibility remaining.
The Nittany Lions are set to be joined by Clemson, San Francisco, and Fordham.