Following on from this answer, I've created an [unanswerable] tag which can be added to unanswerable questions (e.g. this sort of thing which is nice to keep around, but not answerable). If people don't want to see these questions then they can add them to their ignored tags. I haven't found any obvious candidates for an [archive] tag for obsolete questions (e.g. about bugs in superceded versions of EnergyPlus/OpenStudio/SketchUp) but I'd suggest the same approach. Perhaps it could be usefully applied to questions where the user has stopped responding to requests for further information such as this one, or perhaps [unanswerable] is appropriate there too.

This makes not seeing these questions an opt-in decision and so it will not affect general users. It will however help users who like to trawl through older questions for any which may have been missed.

If there are questions that you feel should be removed and you don't have enough karma to close the question yourself, you can email unmethours@bigladdersoftware.com and someone will clean it up.

Closed questions will remain on the site, but they shouldn't show up when filtering.

How about we also add an answer to those questions that says "This question appears to be unanswerable." That way it does not show up when looking for new questions to answer.

Since unmethours is about software development where questions may become outdated with new releases anyway, I would propose not to delete questions as a general rule but to create an archive where one could dig in case someone discovers a need to do so. In this way outdated questions are no longer shown among unanswered questions regularly but still could be retrieved, if necessary.