Should I unaccept an answer if it becomes obsolete?

Question

I accept an answer to my question. Years later, the question still stands but the answer is obsolete and there may be a more appropriate answer.

Should I unaccept it?

There are some small variations:

• If there are now two good answers to the exact same question, I think the right approach is to update the answer to clarify the subtleties and provide all answers in one place, in suitable context.
• If there are now two good questions, the right approach is probably to clarify the question and ask a new one.
• But the topic of this question: if the original answer is now obsolete, and has only historical value, but the original question is still relevant: is it correct to say so in a comment and accept a new more relevant answer or no answer?

This question deals with comment etiquette in such situations.

Answer 1

I don't believe you should do anything, if only because it is very impractical.

The lion's share of accepted answers won't be unaccepted, simply because many users won't go through their old answers, and other users never show up again after they got the answer they needed.
However, if you think a newer/updated answer is a better answer to your question (and still actually answers the question as it is written!) there is of course no problem in unaccepting an older and accepting a newer answer.

Accepted answers should not be confused with objectively right answers - they are usually answers the OP thought were correct for them (for their situation, at that moment, with their configuration, &c.).
Instead, we have voting to reflect the community's consensus; to reflect what the majority considers to be generally right.

Commenting to point out an answer is obsolete is never a bad way to deal with it, and a lot more communicative, because it immediately points out why an answer might not be useful to those facing a similar problem now.

Remember that we'll soon have version labels for answers, which will provide a cleaner way of dealing with this situation in many scenarios.