Open Windows Security
Begin typing Windows Security into the search box.
Open the Windows Security App
Select Virus and Treat Protection, then select Scan options
Run Full Scan and Offline Scan
There are two scans which are recommended, Full Scan and Microsoft Offline Scan, which have to be done one at a time.
This will take some time to complete.
Select one of the Scans and click Scan Now.
When this is run, run the second scan