This has been noted a few times, but maybe not seen as a Feature Request so far:
Please add an option to remove/hide the whole Sign in row when embedding Forms.
It destroys the whole experience of having something embed into another system, when a sign-in appears. This counts for website, but even more when you embed a form in a closed area, where people already had to sign in to. Now, they see another “Sign in” and have no idea that this is about Coda.