I know this is possible in Yjs: replace the key itself with a new instance of a text CRDT, and populate it with the latest value. Such a change will destroy any concurrent edits, however (concurrent changes will be overwritten by the new instance of the CRDT upon merge). A more complex solution is garbage collection, which depends on the internals of the CRDT. I don't think Yjs exposes this for specific edits in text fields.

Automerge... the same approach would work but Automerge advertises itself as storing the full history, so I think the history of the root object would leak the data. I am not sure if it's possible to erase such history with Automerge.