How do I do with Version El Capitan 10.11.6
Get rid of malware in Safari from MacKeeper
Get rid of malware in Safari from MacKeeper
First try
How to install (Really remove) adware
https://discussions.apple.com/docs/DOC-7471
Stop pop-up ads and adware in Safari
https://support.apple.com/en-us/HT203987
Adware Removal Guide : Identification
http://www.thesafemac.com/arg-identification/
Next if necessary:
Malwarebytes Anti-Malware for Mac
How do I do with Version El Capitan 10.11.6