You have canceled an event or created it incorrectly. You can easily remove the event from your account.
To delete an event, click Events in the left main menu, select your event from the list, and then click Settings.
Scroll down to the bottom.
Click on the red button Delete Event.
You will be asked if you really want to delete your event. If you want to delete your event irreversibly, click ok.
ATTENTION:
A deletion of your event cannot be reversed!