Make sure you decrypt your files and folders before removing the app.
Then:
Start by quitting the MacKeeper application.
Open the application folder.
Click on MacKeeper and drag it to the trash can.
The system might prompt you to add the administrator password. Simply enter it and select okay.
MacKeeper software will be moved to the trash can.
The screen will show you another pop-up, just like the administrator password one. It will ask you if you are sure you want to remove or uninstall this app.
You will have to enter the password again and click okay.