i used CCleaner and it forces all apps you want to close if they are trying to refuse. i ended up after doing that going to control panel which can be done by typing it in the bottom left of your screen. after this is done i recommend going to programs and under neeth it should say uninstall a program after this is been clicked find opera and delete it then if you want you could try reinstalling it to see if the virus has been deleted off of your browser 
and btw i dont knowif that works but atleast try