Already discussion on it
http://www.google.com/search?q=Download+Anti-Virus+number-1&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official&client=firefox-a

Likely, there a still some files or processes left after removal. Since you want free solution I recommend you to remove it manually. That’s the only truly free method. Detailed manual removal guide with a list of Anti-Virus number-1 files can be found here: http://www.2-spyware.com/remove-antivirus-number-1.html

if i get it right, your security program wasn’t able to delete antivirus number-1. here’s Anti-Virus number-1 removal tutorial: http://www.spywarevoid.com/anti-virus-number-1-removal-remove-antivirus-number-1.html