Board Thread:Support Requests - Getting Technical/@comment-5577837-20121217210241/@comment-3335785-20121218004936

Terms of use prohibit generally prohibit removing any part of the wikia skin including advertising on a global level. You are free to do whatever you want on a personal level, assuming you know how to. I believe monobook is not subject to the terms not having advertising or any real link to Wikia outside the wikicities portlet in the sidebar and the links to Wikia in the footer.

If you have a MediaWiki page to change it, it is normally within the terms, if not the you are likely not meant to touch it. Adding extra stuff in is also normally within the terms, although there are grey areas with this.