Learning → Discussions needs a course picked first. Filter by author or message and by scope (course-wide or lesson). The list is not paged (it stops at 2,000 threads).
Columns: Author, Message, Scope, Pinned, Posted. Actions: Pin / Unpin and Delete (a thread and all its replies, after a confirmation). There is no hide and no staff reply, although the permission text says "hide".
Student side
Only an active enrollment can read or post. Messages are plain text up to 5,000 characters, one reply level, 30 posts per hour per address. A cancelled student loses access to the thread, though old posts stay. This is the course's own discussion, not the Community plugin.