This feature can be integrated into the client as part of the deletion process. However, the private key will remain active, and if it's compromised, there's a possibility I won't even be aware, especially if I'm not actively using nostr 🤷♂️
Discussion
Yes, you can try requesting to delete notes using above tool. If your privkey is somehow leaked then someone else can post under the same key.
You can try the tool, state I am abandoning these keys forever, and optionally hit delete.