I have removed a few casta dimmers and pico switches from my Caseta app, They aren’t showing anywhere in the Lutron app and as far as I can tell they are not cached anywhere, but they are still showing in the Lutron Caseta integration.
I have the ability to disable them but I would rather they are just not in the list of devices at all.
I am hesitant to delete the integration and re-add it as I have 64 devices currently set up and it would be a pain to re-name them all.