I downloaded some torrent and now my Mac's default search engine changed and idk what more malware has done to my pc. Do you guys know of any free malware remover toolkit or antivirus which can remove this malware.
Why don't you simply put back the most recent backup?
I'd reinstall the whole thing at least. Wipe the whole drive and then restore the last clean backup. Do a clean reinstall and restore a clean backup on top of that. Good luck dudes.