java remove pdf signture

import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

import com.lowagie.text.DocumentException;
import com.lowagie.text.pdf.AcroFields;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfStamper;

public class RemoveSignture {
    public static void main(String[] args) throws FileNotFoundException, DocumentException, IOException {
        PdfReader reader = new PdfReader("C://test.pdf");
        AcroFields acroFields = reader.getAcroFields();
//        ArrayList names = acroFields.getSignatureNames();
        acroFields.removeField("poName");
        acroFields.removeField("agentName");
        PdfStamper stamper = new PdfStamper(reader, new FileOutputStream("C://test1.pdf"));
        stamper.close();
        reader.close();
    }
}