Pimcore\API\Plugin\Broker::unregisterPlugin PHP Method

    public function unregisterPlugin($plugin)
    {
        if ($plugin instanceof AbstractPlugin) {
            // Given a plugin object, find it in the array
            $key = array_search($plugin, $this->_plugins, true);
            if (false === $key) {
                throw new \Exception('Plugin never registered.');
            }
            unset($this->_plugins[$key]);
        } elseif (is_string($plugin)) {
            // Given a plugin class, find all plugins of that class and unset them
            foreach ($this->_plugins as $key => $_plugin) {
                $type = get_class($_plugin);
                if ($plugin == $type) {
                    unset($this->_plugins[$key]);
                }
            }
        }
        return $this;
    }