Piwik\Plugin\Manager::deletePluginFromFilesystem PHP Method

    public static function deletePluginFromFilesystem($plugin)
    {
        Filesystem::unlinkRecursive(PIWIK_INCLUDE_PATH . '/plugins/' . $plugin, $deleteRootToo = true);
    }

 private function makeSurePluginIsRemovedFromFilesystem($plugin)
 {
     Plugin\Manager::deletePluginFromFilesystem($plugin);
 }