I don't want my wiki to be spammed on pages I don't want to be spammed.
Assuming you mean disable anonymous users from editing go to Special:AdminDashboard, look for the setting "Require all contributors to log in" at the bottom right and enable it.
Wait I don't see it
You never told us the wiki, so we can't be sure why you don't see it, but some wikis have it permanently enabled, so you won't see the setting.
It is labeled other and is called infinite wiki
Please give a link... Google search didn't turn up anything.
Um you have to click start a wiki and when you type infinite in they show you two wikis
Just give a link... do you not know how to do that?
What do you think?