Martell, who transferred from Ohio State last season with hopes of winning the starting quarterback job, never found a role with the Hurricanes. He alternated between playing quarterback and receiver in 2019, finishing with seven carries for 7 yards and completing one pass for 7 yards.
Martell was suspended for the season opener last week against UAB, leading to his decision to opt out. Earlier in the week, Martell tweeted photos of himself working out, including the caption, "The work doesn't stop."
An ESPN 300 player in the class of 2017, Martell spent time as a backup quarterback at Ohio State before moving on to Miami.