To delete a meeting that you no longer need:
navigate to the "Meetings" page
click on the Settings menu to the right of the meeting (the button will show as soon as you hover over that meeting)
select "More details"
click on "Delete meeting" button
confirm your choice
Note:
Only the meeting host can delete a meeting
A host can't delete a meeting that is in processing status
Deleting a meeting removes it from all participants' pages