Dropping XMLIndex group and parameters

I have created structured part for the XMLIndex with this command.

BEGIN
  DBMS_XMLINDEX.registerParameter(
    'XXX',
    'ADD_GROUP GROUP YYY
       XMLTable TABLE_NAME ''/entity/year''
         COLUMNS year BINARY_DOUBLE PATH ''text()''');
END;
/
ALTER INDEX INDEX_NAME PARAMETERS('PARAM XXX');

XXX - is a parameter name YYY - is a group name

I don't remember XXX and YYY names now and can't drop group and corresponding parameter.

Q: How could I list all parameters registered for XMLIndex?

You can find out the group name by looking at parameters value returned by following query.

    select index_name, parameters from user_xml_indexes;


    <parameters>
      <structured>
        <group name="YYY">
          <xmltab name="TABLE_NAME"> &apos;&apos;/entity/year&apos;&apos; columns &quot;year&quot; integer  PATH &apos;&apos;text()&apos;&apos; </xmltab>
        </group>
     </structured>
    </parameters>

XXX is not needed after it has been used and is no longer tied to the index. It is only used as a buffer for index definition.