Need To Remove Jounal File After : Transfer/apply To Secondary Db

We are using log shipping and we would like to remove all transfered and applied journal (in the primary box).
We have the intentionto use a trigger like this :


CREATE TRIGGER del_log
ON log_shipping_plan_history
AFTER INSERT
as
declare
@lastfile nvarchar(256)
SELECT @lastfile=i.last_file
FROM log_shipping_plan_history e INNER JOIN inserted i ON e.sequence_id = i.sequence_id
where i.activity=1
begin
if IF (@lastfile <> NULL)
...
... remove file (using xp_cmd for example...)
...
end

but the problem is that we have only the last file transfered and applied that will be removed
(some time, more that 1 file are applied in one shot ...
see num_files column in log_shipping_plan_history).

Any solution to remove all the files generated before the last one given by the query ?
Any other solutions (sql wizard gives the possiblity to to remove file after a laps of time 1hour, 1day...).

I am looking for the table that contains all the journal files (that we can see when we try to retore a db) ?

Thanks