Then use command promth or DOS or whatever your system has, because it does have some kind of promth.
On my computer (XP) I hold down (F8) and I get a list of choices. If I choose (Start up only using command-promth) windows will not start at all, so there will be no way that anything would be blocking you from deleting the file, because the makers of the viruses may be smart, but they won't suspect anyone going back to basics, unless it's a really really old virus
Be very careful when using it, because deleting the wrong file usually is a bad thing
In the threadlink I posted before there is a link to how the promth is used + some other instuctions. read both carefully if you haven't tried it before
Also when cleaning spyware and viruses it often isn't enough to just use antivirus or antispyware. After deleting malware it is often good to use a registrycleaner as well. There is a link to a free one in that same thread
don't reboot before using it. Instead use it right after doing your malware sweep