To remove a virus manually, first identify the virus:
Upload your suspected file to VirusTotal. If it is a virus, use a data shredder software to delete it.
Most common places for malware to hide:
c:/Users/<YourUsername>/ (and subfolders)
Startup folder (type shell:startup in run)
Temp folder (type %temp% in run)
and so many more... but using AV software is the easiest. If not use hitman prohttp://www.surfright.nl/en/hitmanpro
It is the best virus scanner out there (even better then malwarebytes <which i also recmmand>)