Allow deletion of events via API

It would be necessary to be able to delete event from ODP via API. I have two uses in mind for this.

1. Currently there is no way to delete incorrectly created events. Mistake in data load or integration can cause unwanted event data and we would need a way to clean them away.

2. This would allow companies to implement data retention policies. According to GDPR we need to define for how long data is stored. The definition could vary based on the type of the data. Having option to delete data via API would give the users the possibility to implement the data retention policies in their own way.