I gave a second chance to new opera on os x and I'm having a lot of problems.
There is no way to edit or remove default search engines. However I found that browser determine from where you are so it automatically set you some localisation including search engines and some speed dial examples. Found online that file which defines it is located in opera version folder /Resources called default_partner_content.json. Editing this file could cause opera to start without your settings and with only one (safe mode) search engine and that one is google.com, and so this could be fine if you could set your search engine to be default instead of google.com. But you can't! with some more investigation a found that when I changed the file it changed the hash and the file CodeSignatures in folder of the same name in opera version folder contains sha1 base 64 type hash of all files inside opera version folder. I changed that too, and the next thing is that now this file has another sha1 hash. If you look two folders up you could find another CodeSignatures folder with the same named file inside which contains all hash info for files till opera version folder. And I changed there hash info for the CodeSignatures first I mentioned before. All it would be done , someone could think but If you start opera again it shows only google (safe mode I suppose) .

I'm having difficulties using wikipedia search because it searches on my native language and results are incomplete. Any help would be great!