Remove last row in table

I have a form that I allow the user to determine how many rows will be displayed in a table.  I am using a drop down list and use the following code. I would like no table rows to display when zero is selected but the last row is always displayed even when zero is selected.  How can I remove the last row.

var iRows = xfa.event.newText;

if (iRows == "0") {

    //What code should go here

}

else {

    TextField1.rawValue = iRows;

    TrainingReport.TrainingTable.TrainingData.instanceManager.setInstance s(iRows);

}