code: public void delete(String name) throws IOException {
          if (name.equalsIgnoreCase(QUALIFIERS)) {
              policyQualifiers = Collections.emptySet();
          } else if (name.equalsIgnoreCase(ID)) {
              throw new IOException("Attribute ID may not be deleted from " +
                  "PolicyInformation.");
          } else {
              //ID may not be deleted
              throw new IOException("Attribute name [" + name +
                  "] not recognized by PolicyInformation.");
          }
      }
docs: Delete the attribute value.