Reinstall "MacKeeper," then remove it as follows. First, back up all data.
"MacKeeper" has only one useful feature: it deletes itself.
Note: These instructions apply to the version of the product that I downloaded and tested in early 2012. I can't be sure that they apply to other versions.
IMPORTANT: "MacKeeper" has what the developer calls an “encryption” feature. In my tests, I didn't try to verify what this feature really does. If you used it to “encrypt” any of your files, “decrypt” them before you uninstall, or (preferably) restore the files from backups made before they were “encrypted.” As the developer is not trustworthy, you should assume that the "decrypted" files are corrupt unless proven otherwise.
In the Finder, select
Go ▹ Applications
from the menu bar, or press the key combination shift-command-A. The "MacKeeper" application is in the folder that opens. Quit it if it's running, then drag it to the Trash. You'll be prompted for your login password. Click the Uninstall MacKeeper button in the dialog that appears. All the functional components of the software will be deleted. Reboot.
☞ Quit MacKeeper before dragging it to the Trash.
☞ Don't empty the Trash. Let MacKeeper delete itself.
☞ Don't try to drag the MacKeeper Dock icon to the Trash.