A transmission management system stores association information that associates, for each one of a plurality of starting terminals, starting terminal identification information for identifying the starting terminal capable of requesting to start communication with one or more candidate counterpart terminals, and candidate counterpart terminal identification information for identifying each one of the one or more candidate counterpart terminals. In response to receiving a request for deleting at least one candidate counterpart terminal selected from the one or more candidate counterpart terminals, for at least one starting terminal selected from the plurality of starting terminals, the management system specifies candidate counterpart terminal identification information of the selected candidate counterpart terminal using the association information, and deletes the candidate counterpart terminal identification information of the selected candidate counterpart terminal from one or more candidate counterpart terminals being associated with the selected starting terminal.