All admins are typically listed on this page: doki-doki-literature-club.wikia.com/wiki/Special:ListUsers/sysop
As none are listed, it's very likely Caitlyndoodles is the only admin.
I agree it's unnecessary, and we now have other galleries where those images could be added.
Sadly, only admins can delete pages and it seems that the founder has abandoned the wiki. I'm not sure if this wiki even has any admins. :(