A USC product, the 24-year-old Carswell suffered a torn ACL in his first day with the 49ers last June.
According to the NFL’s Friday transactions, Carswell was waived without any designation, so his departure was not connected to a failed physical.
Carswell signed with the Raiders as an undrafted free agent in 2012 and spent training camp and the preseason with the club. He also had a brief stint on the club’s practice squad.
The 49ers have 73 players on the roster, including nine wide receivers.