How do I remove MPlayer X from my MacBook Pro?

try downloading clean my mac and use its uninstall feature or maybe try another uninstaller

http://macpaw.com/cleanmymac

Personally in my testing of the supposed "cleanup" apps, I found them to be either worthless or dangerous with a few being both. So I strongly recommend against using or installing them.

I bought clean my mac and I've been using it for quite somme time and didn't see anything negative about it not to mention its MacWorld Editors Choice and recommended by Cult Of Mac

I would not trust Cult of Mac about anything they claim.

All I can say is that I was certainly glad that when I was testing it I had it installed on its own disk because after the problems in caused during my testing, it was certainly easier to restore the disk rather then having to troubleshoot exactly what damage CleanMyMac had done to the disk.

alright dude.. don't use cleanmymac

use one of the applications on the app store... apple wouldn't add an that would harm your device!

Simbooster Lite - Free

https://itunes.apple.com/us/app/simbooster-lite/id882312406?mt=12

The real MPlayerX is just a self-contained application that you can quit and drag to the Trash. However, it's often redistributed as an installer package that also contains malware. If you are having problems with excessive ads on web pages, ask for instructions. You do not need to download anything to solve that problem, no matter what you may be told.