We plan to introduce support for tracking deletes in the change feed. Using this capability, you can integrate with Azure Functions or another event processing system to perform operations like execute procedure or call other services programmatically.
This is not currently on our road map. However, we will look at this in our next feature review and will provide update on status.
Thank you.gregFDS commented
The ability to delete all data in a collection associated with a specific partition key (tenantId, etc) would be a huge help. This would allow us to drop a tenant's data in DocumentDb without having to delete each document individually.