system/Model.php
public function purgeDeleted()
	{
		if (! $this->useSoftDeletes)
		{
			return true;
		}

		return $this->builder()
						->where($this->deletedField, 1)
						->delete();
	}
public function purgeDeleted()
	{
		if (! $this->useSoftDeletes)
		{
			return true;
		}

		return $this->builder()
						->where($this->deletedField, 1)
						->delete();
	}
Permanently deletes all rows that have been marked as deleted
through soft deletes (deleted = 1)

@return boolean|mixed