How to remove virus without using anti-virus?

Hi! Guys,
My computer have a Trojan horse virus. Then I tried to scan the whole computer with my upgraded Antivirus. It detected the files that infected by Trojan virus. My problem is, I can't remove or heal my file.
Guys, please help me on how to remove Trojan virus? Is there any way like using the CMD to remove Trojan virus? I can't reformat my computer because I have lots of files that are saved on my computer. If I back up it on my external drive, then it will also get infected by the virus. Any idea guys? Please, I really need suggestions.
Thanks.
