CheckBox1是GridView1中一个ItemTemplate里的一个CheckBox
CheckBox2是全选CheckBox
Button1是取消按钮
Button2是删除按钮
注意：CheckBox2必须设置AutoPostBack="True"

//////////////////取消选择按钮单击/////////////////////////   
protected void Button1_Click(object sender, EventArgs e)
    {
        CheckBox2.Checked = false;
        for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
        {
            CheckBox cbox = (CheckBox)GridView1.Rows[i].FindControl("CheckBox1");
            cbox.Checked = false;
        }
    }
//////////////////////删除按钮单击/////////////////////////
    protected void Button2_Click(object sender, EventArgs e)
    {
        for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
        {
            CheckBox cbox = (CheckBox)GridView1.Rows[i].FindControl("CheckBox1");
            if (cbox.Checked == true)
            {
                SqlDataSource1.DeleteCommand = "DELETE FROM table WHERE (id=@id)";
                GridView1.DeleteRow(i);
            }
        }
        GridView1.DataBind();
    }
//////////////////////////全选CheckBox改变后/////////////////////////////////
    protected void CheckBox2_CheckedChanged(object sender, EventArgs e)
    {
        for (int i = 0; i <= GridView1.Rows.Count - 1; i++)
        {
            CheckBox cbox = (CheckBox)GridView1.Rows[i].FindControl("CheckBox1");
            if (CheckBox2.Checked == true)
            {
                cbox.Checked = true;
            }
            else
            {
                cbox.Checked = false;
            }
        }
    }