Toronto FC has declined options on goalkeeper Clint Irwin and forward Tosaint Ricketts.
Defender Jason Hernandez and forward Jordan Hamilton, meanwhile, will both be out of contract at the end of the year.
Toronto could still bring all four back as it could with Brazilian defender Auro and Argentine forward Lucas Janson, whose loan deals expire Dec. 31.
GM Tim Bezbatchenko said negotiation will continue with the players in question.
Toronto also agreed to terminate the contract of midfielder Ager Aketxe by mutual consent.