For the record: Evenium is not the owner of the database - only the host. It is up to the event organisers - who own the database - to delete their events (see Terms and Conditions).
Go under the Configuration --> General info tab
Once on this page, you can delete your event by clicking on the Delete button 
CAUTION:
- Once the event is deleted, there is no way to get it back. This action is irreversible.
- Deleting an event will automatically delete the guests list, the website, the registration form, the emails and the related options’ information.
- If you want to keep an example of the website, registration form and emails of an event, we invite you to duplicate it before deleting it.