code: public void delete(String name) throws IOException {
          if (name.equalsIgnoreCase(DN_NAME)) {
              dnName = null;
              dnPrincipal = null;
          } else {
              throw new IOException("Attribute name not recognized by " +
                                    "CertAttrSet:CertificateIssuerName.");
          }
      }
docs: Delete the attribute value.