Only the owner can delete a space, and only when:
- the space has no expenses yet, or
- the owner is the only member with a NEXO account left (offline members don't count).
Then open Manage Space → Danger zone → Delete space. This permanently deletes the space and all its shared expenses. It can't be undone.
If other people are still in a space that has expenses, it can't be deleted, because it's their history too. Hand ownership to someone else and leave instead (see How do I leave a shared space?).