how to clear a variable?

See following sample code, how do I reset or clear  v_testtable for next loop fetch?

Thanks

declare

TYPE testtable2_aat IS TABLE OF testtable2%ROWTYPE  INDEX BY PLS_INTEGER;

v_testtable2 testtable_aat;

begin

  loop -- main loop here

      -- exit main loop condition test here

select 

1,2,3,4,5

BULK COLLECT INTO 

v_testtable

from 

testtable

        where ....

;

dbms_output.put_line(nvl('1 '||v_testtable.last,-1));

FORALL i IN v_testtable.first..v_testtable.last 

INSERT INTO testtable2

VALUES v_testtable2(i);

  commit;

-- *******

-- Need to clear the variable

-- both following not work

v_testtable2 := null;

clear all from v_testtable2 ;