How To Delete Notifications from Worklist for Specific users in 11i?

Request to provide the steps to delete all the notifications. (EBS version: 11.5.10.2)

1. Ran Purge Obsolete Workflow Runtime Data with parameter as INV: Move Order Approval.

But it didn't purge any notification record. Count is same before and after the program.

2, Ran the following update script but it didn't delete any notification record.

begin

wf_purge.items( itemtype => 'INVTROAP',

itemkey => null,

enddate => sysdate,

docommit => TRUE,

force => TRUE,

purgesigs => 1);

end;

*********Total count on following query -> 169,327

select count(1) from wf_notifications wn, wf_items wt

where wn.item_key = wt.item_key

and wt.item_type = 'INVTROAP'

and wn.end_date is not null;