pocketmine\plugin\PluginManager::disablePlugin PHP Method

    public function disablePlugin(Plugin $plugin)
    {
        if ($plugin->isEnabled()) {
            try {
                $plugin->getPluginLoader()->disablePlugin($plugin);
            } catch (\Throwable $e) {
                $this->server->getLogger()->logException($e);
            }
            $this->server->getScheduler()->cancelTasks($plugin);
            HandlerList::unregisterAll($plugin);
            foreach ($plugin->getDescription()->getPermissions() as $perm) {
                $this->removePermission($perm);
            }
        }
    }