Other way to disconnect user/client in mySql 5.6?
Enforcing limits: ALTER USER and set MAX_USER_CONNECTIONS.

If you where using MariaDB you'd have KILL USER

Otherwise, for MySQL and non-MariaDB, for killing off connections try the following SQL:

select @kill := GROUP_CONCAT(CONCAT('KILL ',  id, ';')) FROM information_schema.processlist WHERE user = $id;;
PREPARE stmt FROM @kill;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;