There used to be a facility for posters of questions to close the question but it has gone- either as part of or shortly after the launch of the new improved Answerbank.
All I can suggest is to post a reply to your own question saying "Thank you but no more answers please"
If you are desperate you could ask other users to report the thread and it may get removed.
Or you could email the Ed and ask for it to be closed- he or she may still have the facility because I'm sure I have seen the odd closed thread
You could close threads upto a few months ago (it was introduced as part of the new AB)
But of course some users started to abuse the system by posting threads to state their opinion on something or somebody and then closing it straight away so nobody could reply. so the feature was taken away.