Board Thread:Support Requests - Getting Started/@comment-5518342-20130817171713/@comment-4018164-20130817173030

The first thing to do is to block that user and hist IP, or just the IP if it's an anonymous user.

About your question, you can also ask wikia to disable anynymous editing for maybe up to 2 weeks, but you would need a really good reason for this (e.g. high level of vandalism).

Also if your wiki is one of those that are listed as wikis that mostly attract children, wikia may disable editing of anonymous users due to COPPA.