code: public void delete(String name) throws IOException {
          if (name.equalsIgnoreCase(USAGES)) {
              keyUsages = null;
          } else {
            throw new IOException("Attribute name [" + name +
                                  "] not recognized by " +
                                  "CertAttrSet:ExtendedKeyUsageExtension.");
          }
          encodeThis();
      }
docs: Delete the attribute value.