Hi Hayasaka,
As you are working on Traditional Web you need to explicitly AJAX refresh the part of the screen you want.
On your ShowEditableTableRowDelete action you don't have an AJAX refresh, therefore you screen doesn't refresh. On your ShowEditableTableRowSave action you two AJAX refresh after the for each which are refreshing a part of your screen which includes the counter.
You just need to refresh the query, do the for each to get the cumulative and do the same AJAX refresh after DeleteMain in your ShowEditableTableRowDelete action, just like you did on your ShowEditableTableRowSave action.
See here more information on AJAX refreshing screen elements in OutSystems Traditional Web applications.
Hope it helps.
Regards,
João