To get rid of Nation Zoom malware you can't simply remove the browser add-on. There are some files related to this malware which actually restore it again, even after successful removal. So, you definitely need to scan your PC with some powerful antivirus that will detect this file and will remove it. You may try Malwarebytes, free program. I think it should be poweful enough to detect Nation Zoom and remove it.
You could also try this method - http://www.deletevirus.net/remove-nation-zoom-browser-hijacker-for-free/ This program offers 15-day free trial to remove any malware, including Nation Zoom virus. You may follow the guide there and get rid of Nation Zoom at no cost within that 15-day free trial period.