protected void gvCurdOperations_RowDeleting(object sender, GridViewDeleteEventArgs e)
{
int empId= int.Parse(gvCurdOperations.Rows[e.RowIndex].Cells[1].Text);
SqlConnection con = new SqlConnection("YourConnectionStringDetails");
con.Open();
string st = "delete from [EmployeeDetails] where EmployeeId=" + empId;
sqlcommand cmd = new SqlCommand(st, con);
cmd.ExecuteNonQuery();
con.Close();
BindDataToGrid();//This method is for reloading the grid view data again...
} 

public void BindDataToGrid()
{
SqlConnection con = new SqlConnection("YourConnectionStringDetails");
SqlDataAdapter ad = new SqlDataAdapter("SELECT * FROM [EmployeeDetails]", con);
DataSet ds = new DataSet();
ad.Fill(ds, "Categories");
gvCurdOperations.DataSource = ds;
gvCurdOperations.DataBind();
} 

using System.Data;
using System.Data.OleDb;

namespace DataGridViewOperation
{   
    public partial class Form1 : Form
    {
        int rindex;
        OleDbConnection con = new OleDbConnection("Connection String");
        OleDbCommand cmd = new OleDbCommand();
        OleDbDataAdapter da = new OleDbDataAdapter();
        DataTable dt = new DataTable();
        Boolean bind;
        public string colindex;

        public Form1()
        {
            InitializeComponent();
        }
        
        private void Form1_Load(object sender, EventArgs e)
        {
            LoadGrid();
        }

        void LoadGrid()
        {
            con.Open();
            cmd = new OleDbCommand("select * from emp", con);
            da = new OleDbDataAdapter(cmd);
            da.Fill(dt);
            bind = true;
            dataGridView1.DataSource = dt;
            con.Close();
            //I have set Primary key column value in the DataGridview as Readonly because based on that value we can update record
            dataGridView1.Columns[0].ReadOnly = true;
            bind = false;
        }
 
        private void dataGridView1_CellEnter(object sender, DataGridViewCellEventArgs e)
        {
            //store current row index in the variable
            rindex = e.RowIndex;
        }
        //delete using below code for selected row
        private void button1_Click(object sender, EventArgs e)
        {
            con.Open();
            string query;
            query = "delete from emp where eno='" + dataGridView1.Rows[rindex].Cells[0].Value + "'";
            cmd = new OleDbCommand(query, con);
            cmd.ExecuteNonQuery();
            con.Close();
            MessageBox.Show("Record Information update Successfully", "Customer Information");
        }  
     
 
    }
}

protected void btnDeleteRows_Click(object sender, EventArgs e)
{
 
        foreach (GridViewRow row in GridView1.Rows)
        {
            CheckBox checkbox = (CheckBox)row.FindControl("chkSelect");
 
            if (checkbox.Checked)
            {
 
               int employeeID = Convert.ToInt32(GridView1.DataKeys[row.RowIndex].Value);

                SqlConnection con = new SqlConnection(ConfigurationSettings.AppSettings["con"]);
		SqlCommand cmd = new SqlCommand();
		cmd.CommandText = "DELETE FROM EmployeesCopy WHERE Id="+employeeID ;
		cmd.Connection = con;
		con.Open();
		int numberDeleted = cmd.ExecuteNonQuery();
		
                Lable1.Text = numberDeleted.ToString() + " employees were deleted.";
		
		con.Close();
            }
        }
 }