Custom Resources Lifecycle

I am building some custom resources and had a question around the lifecycle of a stack.

When I create a stack with my resource defined in my yaml file, my custom python script runs the create event and receives the data to create the resources. Now the resources return an ID that will be needed to remove the resource if it is updated or backed out.
Where is this ID stored if I return it, I thought the physicalresourceid would be the place but it has been replaced with
2021/02/09/[$LATEST]add1787e220941c189a343f683da7ea1.

thanks in advance