Removes an existing record from an update file.

   DELETE FILE (file-reference)
         [ KEY (expression) ]
         [ OPTIONS (option,...) ] ;

  If the KEY option is not specified, the current record  is  deleted
  from the file; the file must have the UPDATE attribute.

   FAST_DELETE
   INDEX_NUMBER(integer-expression)
   MATCH_GREATER
   MATCH_GREATER_EQUAL
   MATCH_NEXT
   MATCH_NEXT_EQUAL
   RECORD_ID(variable-reference)