What do you mean "keeps coming back"? With nothing else running? I don't use Windows, but my knee-jerk reaction would be to try removing it in safe mode with nothing else running, see if I can observe several clean scans in a row, and isolate what action brings it back (launching a particular browser, visiting a certain page, etc.)
Looks like Malwarebytes only recently observed this one, so maybe a forthcoming update will improve removal.
You may also want to search the registry and/or filesystem for the MD5 or relevant strings from https://blog.malwarebytes.org/intelligence/2015/05/winyahoo-pup-modifies-chrome-secure-preferences/
if you haven't already, but I doubt that will turn up anything your malware cleaner hasn't already.