in fact, MacKeeper has an uninstaller so it's more than easy to remove it from your Mac, just follow these steps:
1) quit the app
2)drag&drop it to the trash
3) fill in the survey form: just choose one of the reasons why you've decided to uninstall MacKeeper
4) press 'Uninstall' button
and all the components of MacKeeper will be completely removed from your Mac
It's better not to use another apps to remove MacKeeper as they can leave some files and leftovers may be running in the background. If this happened, the best option is to contact support and follow their instructions.