presto-main/src/main/java/io/prestosql/metadata/MetadataManager.java/MetadataManager/dropSchema
class MetadataManager:    @Override
    public void dropSchema(Session session, CatalogSchemaName schema)
    {
        CatalogMetadata catalogMetadata = getCatalogMetadataForWrite(session, schema.getCatalogName());
        CatalogName catalogName = catalogMetadata.getCatalogName();
        ConnectorMetadata metadata = catalogMetadata.getMetadata();
        metadata.dropSchema(session.toConnectorSession(catalogName), schema.getSchemaName());
    }