Find and delete all the adware, maybe in the MacOS setting or in applications

Open Terminal , type in the following

defaults delete com.google.Chrome DefaultSearchProviderSearchURL

defaults delete com.google.Chrome DefaultSearchProviderNewTabURL

defaults delete com.google.Chrome DefaultSearchProviderName

defaults delete com.google.Chrome HomepageLocation

defaults delete com.google.Chrome NewTabPageLocation

defaults delete com.google.Chrome HomepageIsNewTabPage

defaults delete com.google.Chrome DefaultSearchProviderEnabled

restart chrome

then check the setting in chrome://policy
should be no policy set