Board Thread:Support Requests - Community Management/@comment-25752292-20151230053242/@comment--20151230055946

If the bureaucrat has been inactive for at least sixty days or is refusing to respond to messages, you may start a public discussion on adopting the Wiki. Adopting allows you to gain bureaucratic rights. If the Wiki is active with users and other admins you will need to start a blog or forum on your adoption to have people give input if they agree/disagree with you adopting it. Note, that two (or three if needed) users may join the adoption together to all be promoted (be it admin or bureaucrat) if everyone agrees to it. However if you want to adopt it yourself and manage rights yourself after you may do that. You will need the majority of the community to agree with your adoption to succeed.

It looks like you recently left the bureaucrat a message which is good. Asking them would be the first step to go. If they don't respond within a week, I would recommend to start a discussion on you adopting it for the community to give input and then filling out an adoption.