Doctrine\ODM\MongoDB\SchemaManager::dropCollections PHP Method

    public function dropCollections()
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->dropDocumentCollection($class->name);
        }
    }

 /**
  * @param SchemaManager $schemaManager
  */
 protected function dropSchema(SchemaManager $schemaManager)
 {
     $schemaManager->dropCollections();
 }