Hey @BruceC,
you are not expected to. In fact you cannot delete any topic as a user here once it is older than 60 minutes (no replies or not). Postings, a reply in a topic, can be deleted without restrictions. But deleting is not really deleting in NodeBB anyway, true deletion, NodeBB calls its purging, is not available for users at all.
Long story short: We do not want users to delete topics as they tend to delete valuable information for others with that, even when they consider the topic failed or obsolete.
Cheers,
Ferdinand