Yes, you can edit an event anytime. Simply log in and find your published event and click on the edit button on the right upper side of your event. A pop up window will appear and you can click on EDIT MAIN EVENT.
Please note: You can see this icon only if you are logged in and the event is your event.
Your changes have to be reviewed by an administrator, you will get an email when your event is live again. Thank you for your understanding.