How to Get Rid of system-alert.clsecure.org Pop-up Ads from Your PC?

I am redirected to system-alert.clsecure.org again and again as i am surfing on the Internet. What's more, i get a fake warning saying that my PC is infected by viruses, i need to call the phone number to get help. It is free. But i am afraid that it is a scam. 

Yes, system-alert.clsecure.org is one online computer support scam. If your PC is infected by it, your browsers like Internet Explorer, Mozilla Firefox, Google Chrome, Yahoo or Bing will be compromised by it. Consequently, you are not able to get access to the Internet or you are not able to get access to the website you like, but redirected to system-alert.clsecure.org. It will show you a pop-up message saying that your PC is infected by viruses. If you want to get rid of them, call the provided number to get help. However, it is dangerous to call the number, it is just a scam designed by cyber criminals. It will ask you to download and install a program which will be malicious to your computer system, since it may contain computer threats.