How to remove unwanted search engine like Becovi

I have be attacked many times and my credit cards and important information was used by hacker he even uploaded few videos of him in my photos folders!!

Now I have unwanted search engine that keeps pop up by itself which is becovi search engine and force me to use it!!

how can I get rid of this search engine? I dont want to download third party apps. I want better way from Apple.

I have tried to change the default search engine many times, but no success! its still there!

appreciate your advice.