Is it possible to omit the Last Name from the basic MailChimp widget sign-up form?

The basic widget-based subscription form displays Email, First Name and Last Name fields. Is it possible to display only the first 2? We wish to reduce the friction on signup, but I see no obvious way to amend the basic form to do this (either making Last Name a hidden field, or removing it entirely).

While I can login to my MailChimp dashboard and create a custom form for embedding, I'm wishing to continue using the basic Widget form.

It does give the option of marking the Last Name field as "not required" but does not appear to provide a way of suppressing the display of the field entirely.

Perhaps I'm missing something obvious, or is it simply not possible without getting under the hood and tinkering with CSS or php files?

Thanks a bunch for any help you can provide on this!