There are uncountable malware and viruses on the internet which can infect the crap out of your device. You may be able to remove some of these viruses from your device, but some threats are so hard to remove. Your device can even be controlled remotely by these threats. In order to clean your infected computer thoroughly, you have to clean it by installing a new copy of the operating system. When a person installs a new Windows or MacOS in their device, they get a chance to clean the full hard drive. By cleaning up the entire hard drive, malware and other viruses can no longer exist in your computer. It is the one-stop solution for fixing infected devices.
Source:- Clean an Infected Computer