Live ORACLE

DECLARE
  TYPE tb1 IS TABLE OF VARCHAR2 (20);

  TYPE ntb1 IS TABLE OF tb1;                      -- table of table elements

  TYPE tv1 IS VARRAY (10) OF INTEGER;

  TYPE ntb2 IS TABLE OF tv1;                     -- table of varray elements

  vtb1    tb1  := tb1 ('one', 'three');
  vntb1   ntb1 := ntb1 (vtb1);
  vntb2   ntb2 := ntb2 (tv1 (3, 5), tv1 (5, 7, 3));
                                                 -- table of varray elements
BEGIN
  vntb1.EXTEND;
  vntb1 (2) := vntb1 (1);
-- delete the first element in vntb1
  vntb1.DELETE (1);
-- delete the first string from the second table in the nested table
  vntb1 (2).DELETE (1);
END;
/

Multilevel Nested Table