set to 0 to delete them

then I have a step in there that I will have to remove in a subsequent commit. The process as you describe it for a list of set of instances is:

1. commit a change that sets to 0

2. deploy change.

3. Make a new commit removing the step.

In Terraform it's just

1. Commit a change removing the resource.

2. Deploy

No cleanups that might be forgotten. No double commits for something that should just be 1.

Terraform doesn't "lose track" of an identifier. It's state file management is pretty robust and it has built in locking for the shared use case.