Flint has no "remove session" action. For chat sessions, two actions do the job instead, and which one you want depends on whether the work should be recoverable:
- Archive session takes the session out of the activity's list but keeps it. You can open it again and unarchive it while its activity and class are not archived.
- Delete session removes it permanently. This action cannot be undone, and only school owners can do it. These are usually admins, but a teacher-labelled school creator can also hold ownership.
Archiving is almost always what people mean. To archive a session, open it, click the ⋯ More actions menu at the top of the page, choose Archive session, type Archive to confirm, and click Yes. Teachers can archive any session in an activity they own; students can archive their own when the activity has Session archivable switched on and is not paused.
If the work genuinely has to go, ask a school owner: they see Delete session in the same menu, and confirm by typing Delete and clicking Yes. Ordinary teachers who only own the activity, and students who do not own the school, do not see this option. File-upload and assessment submissions are different: activity editors can delete those submissions.
For the full picture — how to find an archived session again, how to unarchive it, and bulk deletion — see Archiving and deleting sessions.