Once someone is given Bureaucrat rights, only they or Wikia can remove them. That's why it's usually not a good idea to make someone a bureaucrat at the same time as making them an administrator. To be a bureaucrat, someone has to prove themselves over time. Mplaya3 hadn't even made any edits here when you gave him full rights in July, so I don't know if you knew him from another wiki and thought it would be okay here.
In order to remove Bureaucrat rights, you will need to send in the request through Special:Contact. Click on the "Contact us" link at the bottom.