Quit the fake "utility" named "K9-MacOptimizer" if it's running, then drag it from the Applications folder to the Trash. Empty. Never install anything like it again. The computer doesn't need to be "optimized," and any web page that says otherwise is a scam.
Often installed along with "K9" is the malicious Safari extension "Omnibar." It must be removed in the Extensions pane of the Safari preferences window. Remove all other extensions you don't know you have a use for. If in doubt, just remove all of them. None is endorsed by Apple and none is required to make full use of Safari.
Do the equivalent in the Chrome and Firefox browsers, if you use either of those.
Never install an extension with the words "Spigot," "Conduit," "Genieo," or "Trovi" in the description, no matter what you think it does. In fact, never install any Safari extension, or any third-party software of any kind, without carefully researching it first. Don't assume that software is safe to use unless it comes directly from Apple or another developer well known to you, or from the Mac App Store.