framework/base/Component.php
public function off($name, $handler = null)
    {
        $this->ensureBehaviors();
        if (empty($this->_events[$name]) && empty($this->_eventWildcards[$name])) {
            return false;
        }
        if ($handler === null) {
            unset($this->_events[$name], $this->_eventWildcards[$name]);
            return true;
        }

        $removed = false;
        // plain event names
        if (isset($this->_events[$name])) {
            foreach ($this->_events[$name] as $i => $event) {
                if ($event[0] === $handler) {
                    unset($this->_events[$name][$i]);
                    $removed = true;
                }
            }
            if ($removed) {
                $this->_events[$name] = array_values($this->_events[$name]);
                return $removed;
            }
        }

        // wildcard event names
        if (isset($this->_eventWildcards[$name])) {
            foreach ($this->_eventWildcards[$name] as $i => $event) {
                if ($event[0] === $handler) {
                    unset($this->_eventWildcards[$name][$i]);
                    $removed = true;
                }
            }
            if ($removed) {
                $this->_eventWildcards[$name] = array_values($this->_eventWildcards[$name]);
                // remove empty wildcards to save future redundant regex checks:
                if (empty($this->_eventWildcards[$name])) {
                    unset($this->_eventWildcards[$name]);
                }
            }
        }

        return $removed;
    }
public function off($name, $handler = null)
    {
        $this->ensureBehaviors();
        if (empty($this->_events[$name]) && empty($this->_eventWildcards[$name])) {
            return false;
        }
        if ($handler === null) {
            unset($this->_events[$name], $this->_eventWildcards[$name]);
            return true;
        }

        $removed = false;
        // plain event names
        if (isset($this->_events[$name])) {
            foreach ($this->_events[$name] as $i => $event) {
                if ($event[0] === $handler) {
                    unset($this->_events[$name][$i]);
                    $removed = true;
                }
            }
            if ($removed) {
                $this->_events[$name] = array_values($this->_events[$name]);
                return $removed;
            }
        }

        // wildcard event names
        if (isset($this->_eventWildcards[$name])) {
            foreach ($this->_eventWildcards[$name] as $i => $event) {
                if ($event[0] === $handler) {
                    unset($this->_eventWildcards[$name][$i]);
                    $removed = true;
                }
            }
            if ($removed) {
                $this->_eventWildcards[$name] = array_values($this->_eventWildcards[$name]);
                // remove empty wildcards to save future redundant regex checks:
                if (empty($this->_eventWildcards[$name])) {
                    unset($this->_eventWildcards[$name]);
                }
            }
        }

        return $removed;
    }
Detaches an existing event handler from this component.

This method is the opposite of [[on()]].

Note: in case wildcard pattern is passed for event name, only the handlers registered with this
wildcard will be removed, while handlers registered with plain names matching this wildcard will remain.

@param string $name event name
@param callable $handler the event handler to be removed.
If it is null, all handlers attached to the named event will be removed.
@return bool if a handler is found and detached
@see on()