Remove border of the cell in a newly created row in an html table

<
script type="text/javascript">
        function Addrow() {
            var table = document.getElementById("successFailure");
            var row = table.insertRow(2);
            var cell1 = row.insertCell();
            cell1.innerHTML = "Format and Store Type";
        }
    </script>

--From the list that i am getting from the controller, i am displaying the data in an html table.

for example

column1    column2    column3     column4
 uk           23        23           23
 x            11        11           45
 y            22        63           22
 z            11        35           46 

--but i needed an row at the second position without border

column1    column2    column3     column4
 uk           23        23           23
 format
 x            11        11           45
 y            22        63           22
 z            11        35           46 

--I did it on onload function. But i want to remove the border of the cell. As "format" is bordered in the first cell. I want to remove the border in the cell. So a blank row is needed 
with text as "format".

Kindly help.