Ask HN: How to quickly remove pages from Googles Index?

Hi,

I run a hobby site that recently got attacked by a spammer who managed to create a load of new pages on my site that got indexed by Google very quickly... Now I am trying to get those pages back out of Google's index to clean up my domains profile... Does anyone know a good way of doing this to get them out quickly??

My site: http://betalyst.com/

You can see lots of spammy pages if you do a site: lookup on Google and I want to get those out ASAP.

Thanks in advance for any advice