Hi Hobbit,
The ‘NCA’ indicated that the user is the netconf user. In order to detect device status, the NMS/SDN controller like AC-DCN will send netconf packet to the device to establish a long-connection.
You can use the cut the access-user username XXX command to force the user to go offline.
Or you can use the kill user-interface nca&vty x command. it's the same result.
Note that the operation may have an impact on your service, please do it at the right time.
Glad to help you! Any further questions, let us know.