src/event/EventMediator.php
public function off($eventType, $listener = null)
    {
        foreach ($this->_eventListeners as $i => $l) {
            if ($l->getType() == $eventType) {
                if ($listener === null || $l->getListener() === $listener) {
                    unset($this->_eventListeners[$i]);
                }
            }
        }
    }
public function off($eventType, $listener = null)
    {
        foreach ($this->_eventListeners as $i => $l) {
            if ($l->getType() == $eventType) {
                if ($listener === null || $l->getListener() === $listener) {
                    unset($this->_eventListeners[$i]);
                }
            }
        }
    }
Removes an event listener.

When $listener is null, this function removes all listeners linked to the event type.

@param string   $eventType Event type
@param Callable $listener  Listener (not required)

@return void