There are times when malware can be so embedded in a system, then even a full scan will not be able to fully remove the malicious files, or worse yet, finds nothing at all. For those cases, running an “offline” scan is recommended or in any case where you need more confidence in clean bill of health from your antivirus software. This feature is built into Windows 10, but Microsoft also makes it available as a stand-alone product. I recently had a request to provide a clean bill of health for a system. I used it to perform a full system scan and provide the scan results to ensure the system was free of malware.
Here is a link to Microsoft’s Defender Offline page