kill sesssion in failover session

Hi...
we are using failover parameter in tnsnames while connecting to database server

(failover_mode =
       (type=select)
       (method=basic)
       (retries=180)
        (delay=15)
)

i am trying to kill session using alter system command or OS kill command on the database server
none of these two way able to disconnect the session permanently, each time i kill the session , the application reconnect with new SID.

how can i kill session in failover mode permanently. so the user will need to exit the application and relog to connect to the database again.