Is it impossible to remove the JS: downloader avast?

 I am having big issues removing "JS:Downloader-FHB trj" on my computer, I already tried all software available, and after detecting and removing than the software says that is clean, but is not in reality, I used everything including the adwclear from bleepingcomputer. The strange thing is that the malware shows when I login the backoffice of my online store (magento), the avast alert shows, and everything on my website can't me touch used because the scripts from the website is not being loaded, is very strange, I'm quite new at this things ofmalware., and I'm sure that is related to my computer and not the hosting because it is only firing on my pc. What should I do?