allow data deployments to have an option where records existing on the target org but not in the source org are deleted. This will in effect allow a full sync between source and target orgs without any manual intervention to clean up data.

Just tested Data Deploy and this feature would definitely be useful for our organization.

This would really help our two use cases below:

1. Using an object as a picklist with thousands of records. The list of records changes fairly often and records are often deleted. It's a hassle to track which items have been deleted and manually delete those using workbench in every single sandbox.

2. Using an object as a master template to create a list. The list of records populate another object everytime an opportunity is created. The business controls this list and so we need to be able to both upsert and delete to sync between sandboxes and production.