Vista - Search Directory

How do i reduce the size of my search directory (s)? When I deleted an entry
under the outlook sub, the email in question was deleted as well. I would
like to clear out about 90% of the stuff that is in there but fear that the
files will be gone as well. I use software that removes tracks of browsing
etc. but does not deal with the search directory. I feel that this is a real
security threat because if this file were to be accessed by someone with less
than good intentions....

Thanks in advance