A transmission management system for managing a plurality of transmission terminals, comprising: a memory configured to store: first association information (64, 65) that associates administrator identification information for identifying an administrator with management terminal identification information for identifying one or more management terminals being managed by the administrator; a receiver configured to receive a request for deleting a specific management terminal from being under management of a specific administrator, the request including specific terminal identification information of the specific terminal to be deleted and specific administrator identification information of the specific administrator; and a data processor configured to delete the specific terminal identification information from the management terminal identification information being associated with the specific administrator identification information by the first association information (64, 65); characterized in that: the memory is further configured to store: second association information that associates, for each one of the plurality of transmission terminals, terminal identification information for identifying a terminal with candidate counterpart terminal identification information for identifying one or more candidate counterpart terminals, to indicate that the terminal is capable of requesting to start communication with the candidate counterpart terminals; and the data processor is further configured to: specify one or more management terminals being managed by the specific administrator other than the specific terminal being deleted using the first association information (64, 65), and delete the specific terminal identification information of the specific terminal being deleted, from candidate counterpart terminal identification information associated with each one of the other management terminals by the second association information. a memory configured to store: first association information (64, 65) that associates administrator identification information for identifying an administrator with management terminal identification information for identifying one or more management terminals being managed by the administrator; a receiver configured to receive a request for deleting a specific management terminal from being under management of a specific administrator, the request including specific terminal identification information of the specific terminal to be deleted and specific administrator identification information of the specific administrator; and a data processor configured to delete the specific terminal identification information from the management terminal identification information being associated with the specific administrator identification information by the first association information (64, 65); characterized in that: the memory is further configured to store: second association information that associates, for each one of the plurality of transmission terminals, terminal identification information for identifying a terminal with candidate counterpart terminal identification information for identifying one or more candidate counterpart terminals, to indicate that the terminal is capable of requesting to start communication with the candidate counterpart terminals; and the memory is further configured to store: second association information that associates, for each one of the plurality of transmission terminals, terminal identification information for identifying a terminal with candidate counterpart terminal identification information for identifying one or more candidate counterpart terminals, to indicate that the terminal is capable of requesting to start communication with the candidate counterpart terminals; and the data processor is further configured to: specify one or more management terminals being managed by the specific administrator other than the specific terminal being deleted using the first association information (64, 65), and delete the specific terminal identification information of the specific terminal being deleted, from candidate counterpart terminal identification information associated with each one of the other management terminals by the second association information. specify one or more management terminals being managed by the specific administrator other than the specific terminal being deleted using the first association information (64, 65), and delete the specific terminal identification information of the specific terminal being deleted, from candidate counterpart terminal identification information associated with each one of the other management terminals by the second association information.