doubt on cell double click event in datagridview in c#

//try following code
//Create following variable on class level not here
// it is just for your testing purpose.
                var AddNewCellIndex = 3;
                var UpdateCellIndex = 4; 
                var deleteCellIndex = 5;
   void dataGridView1_CellDoubleClick(object sender, DataGridViewCellEventArgs e)
        {
            try
            {

                if (e.ColumnIndex== AddNewCellIndex)
                {
                    //you open new form here 
                }
                else if (e.ColumnIndex==UpdateCellIndex)
                {
                    //you open update form or what you are using
                }
                else if (e.ColumnIndex==deleteCellIndex)
                {
                    if (MessageBox.Show("Are you sure you want to delete current row", "Delete", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
                    {
                        //delete code
                    }
                }
                //all other cell click will be ignored.
            }
            catch (Exception)
            {
                
                throw;
            }
        }