index is out of range.must be non-negative and less than the size of the collection parameter name:index

private void Form1_Load(object sender, EventArgs e)
{
try
{
sqlCon.Open();

loaddata();


}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}

private void loaddata()
{
try
{
sqlAdapter = new SqlDataAdapter("SELECT *, 'Delete' AS [Delete] FROM Employees", sqlCon);
sqlCommand = new SqlCommandBuilder(sqlAdapter);

sqlAdapter.InsertCommand = sqlCommand.GetInsertCommand();
sqlAdapter.UpdateCommand = sqlCommand.GetUpdateCommand();
sqlAdapter.DeleteCommand = sqlCommand.GetDeleteCommand();

dataset = new DataSet();
sqlAdapter.Fill(dataset, "Employees");
dataGridView1.DataSource = null;
dataGridView1.DataSource = dataset.Tables["Employees"];

for (int i = 0; i < dataGridView1.Rows.Count; i++)
{
DataGridViewLinkCell linkCell = new DataGridViewLinkCell();
dataGridView1[6, i] = linkCell;
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}

private void dataGridView1_RowsAdded(object sender, DataGridViewRowsAddedEventArgs e)
{
try
{
int lastRow = dataGridView1.Rows.Count - 2;
DataGridViewRow nRow = dataGridView1.Rows[lastRow];
DataGridViewLinkCell linkCell = new DataGridViewLinkCell();
dataGridView1[6, lastRow] = linkCell;
nRow.Cells["Delete"].Value = "Insert";
}
catch (Exception ex) { MessageBox.Show(ex.Message); }
}

private void dataGridView1_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
//try
//{
if (e.ColumnIndex == 6)
{
string Task = dataGridView1.Rows[e.RowIndex].Cells[6].Value.ToString();
if (Task == "Delete")
{
if (MessageBox.Show("Are you sure to delete?", "Deleting...", MessageBoxButtons.YesNo, MessageBoxIcon.Question) == DialogResult.Yes)
{
int rowIndex = e.RowIndex;
dataGridView1.Rows.RemoveAt(rowIndex);
dataset.Tables["Employees"].Rows[rowIndex].Delete();
sqlAdapter.Update(dataset, "Employees");
}
}
else if (Task == "Insert")
{
int row = dataGridView1.Rows.Count - 2;
DataRow dr = dataset.Tables["Employees"].NewRow();
dr["LastName"] = dataGridView1.Rows[row].Cells["LastName"].Value;
dr["FirstName"] = dataGridView1.Rows[row].Cells["FirstName"].Value;
dr["Title"] = dataGridView1.Rows[row].Cells["Title"].Value;
dr["HireDate"] = dataGridView1.Rows[row].Cells["HireDate"].Value;
dr["PostalCode"] = dataGridView1.Rows[row].Cells["PostalCode"].Value;

dataset.Tables["Employees"].Rows.Add(dr);
dataset.Tables["Employees"].Rows.RemoveAt(dataset.Tables["Employees"].Rows.Count - 1);
dataGridView1.Rows.RemoveAt(dataGridView1.Rows.Count - 2);
dataGridView1.Rows[e.RowIndex].Cells[6].Value = "Delete";
sqlAdapter.Update(dataset, "Employees");
}
else if (Task == "Update")
{
int r = e.RowIndex;
dataset.Tables["Employees"].Rows[r]["LastName