It works, just not how you think it does. Edge can do some "helping the user" by trying to figure out what your form fields are looking for and filling in the information even if
autocomplete="off"
is specified..
No, you cannot turn this off from your page or code.
What you can do depends on what the rest of your form content looks like. There's little tricks like this to fool Edge:
<span>First Name:</span>
is replaced with
<span>First N<span class="hiddenSpan">bla</span>ame:</span>