I\'m totally understanding the documentation on expanding the Comments app in Django, and really would like to stick with the automatic functionality but...
This is well documented under customizing the comments framework.
All your app will use is get_form, returning a subclass of the CommentForm with the url field popped. Something like:
class NoURLCommentForm(CommentForm):
"""
A comment form which matches the default djanago.contrib.comments one, but
doesn't have a URL field.
"""
NoURLCommentForm.base_fields.pop('url')