presto-main/src/main/java/io/prestosql/metadata/MetadataManager.java/MetadataManager/dropColumn
class MetadataManager:    @Override
    public void dropColumn(Session session, TableHandle tableHandle, ColumnHandle column)
    {
        CatalogName catalogName = tableHandle.getCatalogName();
        ConnectorMetadata metadata = getMetadataForWrite(session, catalogName);
        metadata.dropColumn(session.toConnectorSession(catalogName), tableHandle.getConnectorHandle(), column);
    }