The recommended option is an antivirus rescue CD.
Most antivirus sites offer a ISO file you can burn to a CD and then boot your computer from. (avira
and bit defender
for example are good ones I used, but there are many many others)
It will run regardless of your system current status and remove malware. Don't use the one from your own antivirus as if it didn't stop this attack, it's likely crap.
The brave-and-foolish men option is using a linux distro (another operating system that runs from the CD), like an ubuntu live cd
download, burn the ISO to a CD and then when booting from it select the "Try Ubuntu" option (their booting wizard is pretty informative).
Then you can navigate to the folders and whatever, and nuke manually the offending files. This is dangerous as you can do mistakes and screw up your system. An antivirus rescue CD should really get rid of your issues in a safe way.