How to stop textbox textchanged event on button click event in asp.net

<asp:textbox runat="server" ID="TextBox1" ontextchanged="TextBox1_TextChanged" AutoPostBack="true"></asp:textbox>
<asp:HiddenField ID="HiddenField1" runat="server" Value="false" />
<asp:Button ID="Button1" runat="server" OnClientClick="setButtonClicked();" onclick="Button1_Click" Text="Button" />

<script>
    function setButtonClicked() {
        document.getElementById('<%= HiddenField1.ClientID %>').value = 'true';
    }
</script>

protected void TextBox1_TextChanged(object sender, EventArgs e)
{
    if (HiddenField1.Value == "false") // No Button1_Click
    {
        // do something
    }
    else // button1_click
    {
        HiddenField1.Value = "false"; // reset the hiddenfield1 value
    }
}