There is an admin at the GTA Wikia who seems to not have much admin qualties seeing his edits. He seems sort of inexperienced. His edits appear to not be quite "organized" for a wikia and ignoring the usual formats/templates. Plus he is underage as well, at the age of 14. Is this a problem for that wikia or any other considering his age? His username is LS11sVaultBoy.
I see you have some local active bureaucrats. It would probably be best to contact them with your concerns. When you have an active community like that, it's important to keep this kind of thing out in the open for discussion purposes.
I contacted the bureaucrat but he apparently lets him do as he pleases, creating small articles and ignoring the wiki's formats. We began creating collections of some of GTA V's small side missions rather than creating multiple small articles. LS11sVaultBoy then started undoing the redirects of the small mission pages. Tom the bureaucrat there told me not to judge him but really? You're going to allow an admin to edit this way and have very few good reasons for his actions? That explains why most of the wiki's articles are terribly edited. I don't think it's necessary for him to have the rank of admin if this is how he handles things. I'm not saying he shouldn't be an editor, just not an admin.
My advice would be to get a discussion going and write a policy on the wiki for the proper format, if you haven't already done so. That way you could show the admin exactly what page should look like, and you could have a concrete policy to show the bureaucrat or Wikia for removal of rights.
If you feel that others are of a like mind, and even if *you alone* feel so strongly about this, start a Forum or Blog to open a civil discussion about removal of the user's admin rights. Because a community has the right to determine who has Rights among them.
It might get a little ugly, and if truly abusive the admin in question may edit and or delete them (so take copious screencaps JIC, even though Staff can still see things removed).
However, such a discussion can then be sent to Special:Contact for Staff to determine if they have need to become involved.
I repeat, keep the discussions civil, recommending all involved to do the same.