The best antivirus to remove malware is Norton, Avast and even Malwarebytes.
I've used these antivirus software's with success for removing malware from my own computers and some friends computer as well.
To permanently get rid of malware, disconnect your computer internet then reboot your computer into Safe Mode, run a full scan antivirus software like Avast, Malwarebytes or Windows Defender and delete/quarantine anything threats.
For severe malware infections you may need to factory reset your device or wipe your computer completely and reinstall a new copy of the operating system or use a bootable USB rescue disk as a last resort.
Wiping a computer completely and then restoring the computer with a fresh operating system will completely remove the malware.
Wiping the computer completely and reinstalling the operating system will restore the computer to factory settings and so the malware will be gone.
If you want to be extra cautious, you can also install a new hard drive to be safe, but wiping the computer completely and reinstalling the operating is enough.
Although if I were gonna wipe the computer anyway then I would just install a new hard drive anyway so I ensure my hard drive wouldn't fail later since I going that far anyway.
To find hidden malware on your computer or device, use a reputable antivirus software like Avast, Malwarebytes, AVG, Microsoft Defender etc and run a deep scan for the hidden malware.
Also check the Task Manager and Activity Monitor for suspicious processes using high resources, especially those with weird names, and review any installed apps and browser extensions for anything that is unfamiliar.
Also look for any signs of system slowness, pop ups or faster battery drains.
You can also find hidden malware using specialized rootkit scanners.
Malware also often hides in startup programs for persistence, review and disable anything that is suspicious in your system's startup settings.
The worst computer virus in history was the MyDoom computer virus in 2004.
The 2004 MyDoom computer virus cost damage that cost $38 billion and spread fast and overloaded servers and also created massive botnets for DDoS attacks.
The 2004 MyDoom computer virus spread rapidly through email attachments and turned infected computers into zombies.
Another worst computer virus in history was the 2017 WannaCry virus.
The 2017 WannaCry virus was a ransomware attack which affected over 200,000 computers in 150 countries, which disrupted healthcare like UK's NHS and even businesses.
The 2017 WannaCry virus encrypted files and demanded ransom payments, and exploited a Windows vulnerability.
And another worst computer virus in history was the 2010 Stuxnet virus.
The Stuxnet 2010 computer virus was a highly sophisticated computer virus worm that physically damaged Iranian nuclear centrifuges, which marked the first cyberweapon targeting industrial control systems.
The Stuxnet 2010 computer virus worm exploited multiple zero-day vulnerabilities to infiltrate Siemens control systems.
And finally another very bad worst computer virus in history was the ILOVEYOU virus that occurred in 2000.
The 2000 ILOVEYOU computer virus infected millions of computers within days and overwrote files and cost billions of dollars, which taught the world about social engineering via email.
The MyDoom computer virus was the absolute worst in history for it's sheer scale and economic cost.
The WannaCry computer virus was also worst in history for it's widespread ransomware impact.
The Stuxnet computer virus was worst in history for demonstrating cyber warfare's ability to cause physical damage.