Deleting it, improving it or simply voting it down seem to be the ways to go (other than simply ignoring it, of course).

Ubuntu help center indicates the first two options. It states that

Answers that do not fundamentally answer the question may be removed

which includes answers which are

barely more than a link to an external site

But it also indicates the possibility of simply improving it.

So the question is whether the fact that the answer is late changes anything here. I personally cannot see why, unless the question clearly has an expiration date which is exceeded.

Deleting it, improving it or simply voting it down seem to be the ways to go (other than simply ignoring it, of course).

Ubuntu help center indicates the first two options. It states that

Answers that do not fundamentally answer the question may be removed

which includes answers which are

barely more than a link to an external site

But it also indicates the possibility of simply improving it.

So the question is whether the fact that the answer is late changes anything here. I personally cannot see why, unless the question clearly has an expiration date which is exceeded.