try this
.hiddencol
{
display:none;
}
.viscol
{
display:block;
}
add following code on RowCreated Event of GridView
protected void OnRowCreated(object sender, GridViewRowEventArgs e)
{
if (e.Row.RowType == DataControlRowType.DataRow)
{
e.Row.Cells[0].CssClass = "hiddencol";
}
else if (e.Row.RowType == DataControlRowType.Header)
{
e.Row.Cells[0].CssClass = "hiddencol";
}
}