Those sort of fake antimalware tools fool antivirus applications I'm afraid and it takes special tools to remove them.
There's an excellent removal guide here: http://www.bleepingcomputer.com/virus-removal/remove-security-tool
Scroll down the page, do NOT click the first links you see as they are all advertising.
Yesterday , my home PC was infected with this Security Tool Virus . My family member who was using the internet did not know it was a virus and thought initally that the messages were genuine .
At that time my PC had only Spyware Doctor from Google pack installed.
I tried to kill the Security Tool virus , but it was not allowing me to open any application or even go into my adds/remove program
Then I started the PC in "Safe Mode with networking" - In this mode only bare programs are activated . Shut down your PC first . Now when you start your PC keep pressing F8 and it will come up with the text screen to choose Safe Mode with networking.
I then installed McAfee Anti virus Internet Security while in safe mode and then shut down the PC and started it in normal mode.
Again the Security Tool virus was activated. But as McAfee came on it was able to kill the Trojan and the security tool virus was for the first time not showing in the right hand tray at the bottom. Then I ran a complete scan using McAfee and it detected several trojan viruses and was able to quarantine it .
Thus the virus was removed. Hope this helps