How To do invisible a column of Gridview

Sometimes we need to do invisible some particular column of a gridview for some cases.This can do as follows.
In below example admin can Only view column 2 and 21.
protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
{
if(user != "Admin")
{
if(e.Row.RowType == DataControlRowType.Header)
{
e.Row.Cells[2].Visible=false;
e.Row.Cells[21].Visible=false;
}
else if(e.Row.RowType == DataControlRowType.DataRow)
{
e.Row.Cells[2].Visible=false;
e.Row.Cells[21].Visible=false
}
}

}