I thought that Methyl would have pre-empted my 'standard response' by now. (It's 'standard' simply because it usually works!).
Download, install and run the free version of Malwarebytes Anti-Malware:
https://www.malwarebytes.org/free/
(When installing, take care to deselect the option to accept a trial of the 'PRO' version. Use the so-called 'quick' scan but don't be surprised if it takes over half an hour to run. When it finishes, click to see the results and then click the option to remove everything that's been found).