how to delete image in folder/directory?

protected void deleteImage_Click(object sender, EventArgs e)
    {
       
        string strConnString = ConfigurationManager.ConnectionStrings["DatabaseConnectionString"].ConnectionString;
        SqlConnection conn = new SqlConnection(strConnString);
        conn.Open();
        SqlCommand cmd = new SqlCommand("Delete From ImageTbl Where id= '" + txt_delete.Text + "'", conn);
        cmd.ExecuteNonQuery();
        conn.Close();
        bindgrid();
        txt_delete.Text = "";
        txt_delete.Focus();
    }