In a statement posted to his Twitter account, Sims wrote, "It was not an easy decision, however, I believe it is the right decision for me at this point in my career."
Sims has been a three-year starter for the Yellow Jackets, throwing for 4,464 yards, 30 touchdowns and 23 interceptions in his career.
This season, he started the first seven games before spraining a foot in a loss to Virginia and missing the final five games.
Earlier this month, interim coach Brent Key announced Sims was going to be away from the team indefinitely.
"We had meetings with Jeff and meetings with the doctors and the medical professionals and came to the determination that it would be best for Jeff to not be in meetings or not be in practice, but to be in treatment and in rehab right now moving forward," Key said at the time.
McCollum had 655 receiving yards and three touchdowns as a sophomore, and was fifth in the ACC this season with 60 receptions.
The transfer portal is not officially open yet, but Sims can enter on Dec. 5. The Division I Council approved in August a new transfer window that opens the day after championship teams are selected and closes 45 days later, on Jan. 18, 2023. There is also a 15-day spring period from May 1-15.