SilcBool silc_client_del_channel_private_key(SilcClient client,
                                                 SilcClientConnection conn,
                                                 SilcChannelEntry channel,
                                                 SilcChannelPrivateKey key);

    Removes and frees private key `key' from the channel `channel'.
    The `key' is retrieved by calling the function
    silc_client_list_channel_private_keys. The key is not used after
    this. If the key was last private key then the old channel key is
    used hereafter to protect the channel messages. This returns FALSE
    on error, TRUE otherwise.