It seems like basic functionality to have a trigger when a Sharepoint list item is deleted, but somehow, that functionality doesn't exist. I'm not sure exactly how you could have created a trigger for when a list item is created and NOT realized, 'hey, maybe we need to have a trigger for when the item is deleted, too'!
Good news - this item is completed, you can read about it in this blog post : https://flow.microsoft.com/blog/share-with-sharepoint-office-365/ - there are now triggers for both When an Item is delete and When a file is deleted. Thanks!