SilcBool silc_client_attribute_del(SilcClient client,
                                   SilcClientConnection conn,
                                   SilcAttribute attribute,
                                   SilcAttributePayload attr);

    Delete a Requested Attribute from the client.  If the `attribute'
    is non-zero then all attributes of that type are deleted and the
    `attr' is ignored.  If `attr' is non-NULL then that specific
    attribute is deleted and `attribute' is ignored.

    You may get all added attributes with the function
    silc_client_attributes_get and to get the SilcAttributePayload.
    This function Returns TRUE if the attribute was found and deleted.