If you want to remove in an unattended way, use the scheduled scan
facilities. There must be an administrator logged in at the time the scan
is scheduled, and nobody has yet found that the scheduler is perfectly
predictable at all times. (i.e. don't post bugs against the scheduler 'til
beta2.
One detail to note is that the default for some threats in an unattended
scan is quarantine, versus removal--this will be the case for Peer to peer
applications such as Kazaa, for example. This is important.