You could try & use a manual removal technique such as those outlined
in the Tech Guides http://www.reedcorner.net/tech-guides/ and look into
the three sections there, Mac Malware Guide, Adware Removal Guide
and Performance Guide; from that page. Also note other details that may
be helpful in course of learning how to track down stuff + where to look.
The above information was by the author of 'Adware Medic' so it pre-dates
the abilities of that somewhat more automatic method; which later become
'Malwarebytes anti-malware for Mac' {the maker Thomas R. is still involved.}
There had been a removal tool for older Mac OS X (intel) before AdwareMedic.
Seemed to me that one didn't see updates, as newer tool worked in later OS X.
Good luck & happy computing! 🙂