Can I cancel if my session is empty?

Yes, if no one has booked the session, which you can see on your attendees list. You can cancel up to 10 minutes after the start of a session. To do so, please leave the session, go to your My Sessions, the session detail page or the schedules page to find the session and click "cancel." See How do I cancel a session I'm hosting.

If you see there are bookings, you can still cancel, but we'd encourage you to wait a bit longer because they might be late. To avoid empty sessions, consider scheduling your sessions more in advance or creating shorter sessions that are easier to commit to.