In theory, reasonably good questions should be left on the site, especially after they have been answered. That way, many people can benefit, not just the OP.
In practice, bad questions are often deleted from SE sites, or the OP is encouraged to delete them. Given that the question was downvoted, the OP may reasonably have believed that s/he was being "encouraged" to delete the question, the answer notwithstanding. In fact, the site awards badges such as peer pressured, for people that delete posts with -3 or lower. Such posts are also penalized by lighter text, etc. And deleting downvoted posts removes the negative points from one's reputation.
Apparently people feel that it was a "bad" but improvable question. Then efforts should have been made to salvage the question, by more experienced site members, if not the OP. People should then re-assess their downvotes based on the improved versions (if any), to help come to a final decision.
At one point, I believe that it was impossible to delete questions on SE sites until after they had been posted for two days, to allow this revision process to take place. Perhaps Italian SE, being a "newer" site, does not have this feature. Perhaps the site should ask for it.