The Patriots' roster now has 88 players, two shy of the NFL's 90-man limit.
Morris, 22, was a three-year starter at Iowa who was just the sixth player in program history to total 400 career tackles. He was a longshot to stick with the Patriots.
This marks the second rookie the Patriots have released just days after signing, as Morris joins Bowling Green tight end Tyler Beck in that category. When that happens, it could be a variety of factors in play, from a player struggling to keep up mentally to physical considerations.
With Morris, the Patriots released him with a "failed physical" designation.