Earlier quoted context omitted.
If you are implementing RAG - which you should be, because training or fine-tuning models to teach them new knowledge is actually very ineffective, then you absolutely can unteach them things - simply remove those documents from the RAG corpus.
I still don't understand the hype behind rag. Like yeah it's a natural language interface into whatever database is being integrated, but is that actually worth the billions being spent here? I've heard they still hallucinate even when you are using rag techniques.
The obvious challenge here is "how do I ensure it can answer questions about this information that wasn't included in its training data?"
RAG is the best answer we have to that. Done well it can work great.
(Actually doing it well is surprisingly difficult - getting a basic implementation of RAG up and running is a couple of hours of hacking, making it production ready against whatever weird things people might throw at it can take months.)