How do I remove W32Blaster.a.Worm from my laptop?

my computer gives the following pop-up messages: Malicious problem detected; firewall warning Security Protection detected a leak of your files etc.; Security Protection Full PC scan and begins scanning, but no matter what I try to do it tries to make me buy this Security Protection Plan which I know is a scam. I have Avira Anti-Virus on my computer and Malware and on my session it doesn't allow me to do anything, but if I log-in on the Guest session they run and say they are deleting 2 files but it doesn't help when I log-in on my session.