Yandex takes over and is a real bother to get rid of, you need to do this before you try to sort out your search bars, it will just keep knocking anything else out. start by un-installing from the control panel, then change the home page, Google chrome may allow you to block this extension too, you need to either give the computer to someone who you trust to do the work or sit with you and go through it, not something that is easy to explain on a forum.