When I downloaded Firefox, I ended up getting Trovi search engine and now can not get it off my computer. Is there something Mozella can help me with?

I downloaded Firefox a few months ago. Once it was on my computer, a search engine called Trovi was coming up every time i tried to search the web. I've tried to delete if off my system and it wont come off. When I go to use my Chrome i cant because this Trovi is on it. And my Firefox search engine is Yahoo, which I don't want. Is there anything you can do to diagnose and fix my computer?