He has technically done this on my server as well.
When it was simply named Ze Operator's Boss Battles: Early Alpha, he used to be an admin on my server. But he would do stuff without asking my permission first, and occasionally micromanage anything that doesn't see favor in the kid's eyes.
The kid, to say the very least, is immature, professionally speaking. Unprofessionally? He's a richard and becomes very rude and angry when he's not in power. Everything with him is a power struggle, and when I fired him he vowed to "Make sure no one gets on to your server" kind of crap. He still comes on occasionally, even if for a sec.
/Support, and maybe if he is reading this, maybe he'll loving learn.