The most active community among Turkish speakers is on Wikipedia.
To answer the other question, we would like to keep the "history" (news content) for archiving purposes, but the wiki should be read-only.
Yes. It isn't the Wikinews community, but the Wikipedia community consensus. As such, the argument on a distinction between voluntary and involuntary closure falls, and discussion on closing tr.wikinews should be on meta with proper notification to trwikinews, which seems to have not been done.
I'm not a member of LangCom.
Closing this, @Superyetkin: After you have provided a discussion on the local wiki as asked for or approval from LangCom via https://meta.wikimedia.org/wiki/Closing_projects_policy, please set the status of this task back to "Open" via the Add Action... → Change Status dropdown. Thanks!