Delete: this is the option if time passes and the user does not acknowledge the community's comments and / or doesn't edit their answer.
The long answer:
There is no right or wrong answer.
Reputation & Moderation
At Stack Exchange, we believe moderation starts with the community itself, so in addition to all users gaining privileges through reputation earned, each site has moderators elected through popular vote.
The "popular vote" hasn't happened yet, since we are in beta, and the community just has pro tempore moderators. But moderators are just "regular guys" with access to the moderator tools. Moderators agree to abide the moderator agreement but they don't go through any kind of special training or "moderator bootcamp" to be able to tell "right from wrong", so to speak.
Also, almost every action can be undone and you can flag for moderator help in whatever you need. I have closed questions I thought were off-topic and then people made me understand a different point of view, so I reopened those questions as a result.
So all that goes to say:
- You should do what you personally feel helps building the Spanish.se that you want to have.
- Don't be too afraid of being wrong/causing harm.
I have found myself there too, specially after being given "moderator
powers responsibilities", and I tend to err on the side of "these people are new, give them time, be nice, etc." Thus said, I think that experience has proven that this is not usually the case and these posts are almost never improved.
I think (especially given those four options) that you should vote to delete. All of the other options seem to be inappropriate and the only thing preventing you to vote to delete is that you want to give additional time (and help) to this user to understand how to answer properly on the stack, come back, and improve their post (which is by the way commendable and laudable).
You also might want to downvote poor answers and, especially, comment to give additional help about what is wrong with the post and what can be improved.
Moderators should address the delete flags (effectively deleting these low quality contributions or comments posted as answers) and, shall this user come back and address the changes to improve their post, they can flag for moderator attention to request moderators to undelete their post (which should be just a learning experience, specially for new members).
Otherwise these low quality contributions would be longing there eternally, with no one wanting to cause harm by deleting them (which paradoxically will cause harm to the site and all users). We should not sacrifice the quality of the content by trying not to be "too rude" to people. As you point out, after all most of these post already have comment-links with support information about how to improve contributions and help understanding the philosophy of the site.
We have a friendly community, we are being friendly and polite to all contributors, and users should not take it personally when something is pointed out about their contributions, especially low-quality ones. All users receive from time to time comments, even in really good answers, noting things that could be improved, "missing cases" or addressing suitability issues due to regional differences, for example. It should not be a big deal.
Don't forget that you can find some templates to give user advice about low quality contributions in out meta-post Lista de comentarios útiles para el sitio.
Thank you, and keep the great work.