From docs:

"If deleting recursively, this bypasses ownership of items contained by the entity.  
That means that if the container_guid = $this->guid, the item will be deleted regardless of who owns it."

Look at this.

An example of how to do this in your class.

If you want to look at the code

https://github.com/Elgg/Elgg/blob/b7b6827e6aa3374670414bb9838d4d39e9a9fd4a/engine/classes/Elgg/Database/EntityTable.php#L561-L563

and

https://github.com/Elgg/Elgg/blob/b7b6827e6aa3374670414bb9838d4d39e9a9fd4a/engine/classes/Elgg/Database/EntityTable.php#L584