It's important that you close your meetings correctly, otherwise they might keep running after you finish! Just hanging up a call won't automatically end the meeting.
Accessing by Web
When you finish your meeting, click the End Meeting button in the bottom-left menu.
If you have held a call or screen-share, you'll be prompted to summarize your call.
Accessing by Telephone
If you've dialed in by phone, just hang-up the call as normal.
Note: if you're also accessing over the web, you're meeting won't end automatically. You'll need to end the meeting from your Web browser.