code: public void delete(String name) throws IOException {
          if (name.equalsIgnoreCase(PERMITTED_SUBTREES)) {
              permitted = null;
          } else if (name.equalsIgnoreCase(EXCLUDED_SUBTREES)) {
              excluded = null;
          } else {
            throw new IOException("Attribute name not recognized by " +
                          "CertAttrSet:NameConstraintsExtension.");
          }
          encodeThis();
      }
docs: Delete the attribute value.