User blog comment:Kirkburn/Technical Update: November 25, 2015/@comment-24531999-20151126002224/@comment-126761-20151126135014

Indeed, Staff can delete them on request at the moment.

Meanwhile, we're working on an update that should allow admins to delete pages from the MediaWiki namespace (since doing so is not a security risk). This may be ready next week.

Update: scheduled for next Tuesday, in fact.