Revoke the user`s certificate or write disable in user`s ccd file, I guess the first option is how it should be done.
Then log on to management interface and type help:
login as: root
root@xxx.xxx.xxx.xxx's password:
ovpn01b>
telnet 127.0.0.1 1197
>INFO:OpenVPN Management Interface Version 1 -- type 'help' for more info
help
Management Interface for OpenVPN 2.3.6 armle-unknown-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [MH] [IPv6] built on Aug 11 2015
Commands:
...
...
kill cn : Kill the client instance(s) having common name cn.
kill IP:port : Kill the client instance connecting from IP:port.
...
...
END
If you kill the connection without ccd disable or revoking certificate, the client can still reconnect.
I`m sure there will be better ways...let`s hear it from the knowledgeable 🙂