How do I prevent auto complete "Use password for:" option in chrome?

Use autocomplete="new-password", as per the specs.

In IE you need to do like this:

<asp:TextBox ID="TextBoxPassword" runat="server" AutoCompleteType="Disabled"></asp:TextBox>

In all other browsers, this:

<asp:TextBox ID="TextBoxPassword" runat="server" autocomplete="Off"></asp:TextBox>

Im pretty sure you need the 'off' to be: 'Off'

In HTML, as you mention you can use the;

<form action="demo_form.asp" autocomplete="on">
  First name:<input type="text" name="fname"><br>
  Last name: <input type="text" name="lname"><br>
  E-mail: <input type="email" name="email" autocomplete="off"><br>
  <input type="submit">
</form

Either on the form or the input itself.

Maybe something else in your code is enabling it again?

Hope this works. Just tested and had no problem. Both IE and Chrome.