Should I delete my now obsolete answer?

Question

Back in 2014 I answered the question Google Spreadsheet generate random numbers with Math.random(), based on how Google Spreadsheets worked at that time: https://webapps.stackexchange.com/a/71355/21583 I included some background as to why I believed Spreadsheets worked that way.

Recently, as Rubén points out in a comment, Google Spreadsheets have changed, so that it now gives a proper error message instead of just timing out, when trying to do what the OP tried. As such, my answer no longer reflects reality, and there are now two other answers that are up-to-date.

Should I now delete my answer, as it is no longer valid, or is the background information it includes still useful for historic/general purposes?

And what is the best way to deal with obsolete answers in general?

Answer 1

You should not delete your answer. Just prepend with a last working date.

I find the idea of users searching around bothering people to delete time dependent answers cumbersome and useless.

Your answer gave value (and reputation) so keep it.

Answer 2

Is the "new" Google Spreadsheets universal? I'm not sure that it is. For those who are still stuck using (or refusing to update from) the old/original Google Spreadsheets your answer may still be useful.

Since it's not accepted, if you have determined that you can't edit it to be correct (at least, not without parroting the up-to-date answers), I guess the decision is up to you as to whether you want to lose the 18 reputation points gained from the answer. Or to prevent the downvotes you're likely to get in the future for being out-of-date.