There are lists of spyware/malware all over the internet. Look them up, or ask me specifically here and I'll send you mine. Then you must go through all your cookies, downloads, and all your apps and folders in settings, especially the system apps, and delete any/all you find on the lists. Using Search helps with that. For those that are just suspicious, because of certain clues that match what you're looking out for, you can disable those in safe mode and test your phone each time for the end of any known troubles. Bet sure to do lots of backups in case of mistakes, but also delete any of those that you've found contain malware.