can't help you unless we know what the trojan is so best advice is get rid of norton & replace it with Bit Defender & Malwarebytes. people asking for help have to supply info if they want reliable help;you didn't do that
Dump Norton , its complete rubbish and get a free anti virus like Avira or Avast.
Its not easy to manually remove a trojan---thats why its called a trojan in the first place.
Put avira anti virus free on your PC,Itll remove,or quarantine it,ive just done this this week,after AVG started playing up,because of the virus,it only takes 5 mins to download it.
I use Norton 360 and was in a similar situation last year and was amazed at how quickly I was able to remove it with SpyBot-SD. It is an established and reputable programme within the industry, easy to use and great at keeping your computer clean and it is FREE.
I sought help within the forum of seriously able techies at Tech Republic as to exactly where my problem lay: in the registry. It's worth signing-up to their site to ask your question. You get immediate responses from IT professionals who make a living from their knowledge.