Threads are removed if they break the
Site Rules. For example they might be removed because they discuss topics that are not family friendly. Or because they have descended into sniping and arguments and it makes more sense to remove an entire thread than it does to remove each individual post because it has all gone so far off topic. Threads might also be removed if they are libellous and could get The AnswerBank into trouble.
Threads that ask why a particular thread was removed are also removed, because the original thread was removed for a reason, and we don't want the topic to be started up all over again. Threads about banned posters are also removed for similar reasons, and because the Eds don't get into discussions about why people have been banned or suspended. We just don't have time to explain every decision we make. And of course, spam threads are deleted too.
The bottom line is, threads are removed because they break the
Site Rules, which can be found here:
http://www.theanswerbank.co.uk/Answerbank-Suggestions/Question965826.html There's nothing secretive about it, and if someone has had a post or a thread removed they should be able to figure out why.
Hope that helps explain things!