Remotec zrc90 custom driver removal error

Now that the latest firmware has an official driver for the Remotec zrc90, I have switched all of mine to use the official driver. For the sake of tidiness I tried to remove the custom driver but get the following message.

Referential integrity constraint violation: "FK_HS4W547FIMWHJI3BGM33PM9PX: PUBLIC.DEVICE FOREIGN KEY(DEVICE_TYPE_ID) REFERENCES PUBLIC.DEVICE_TYPE(ID) (129)"; SQL statement: DELETE FROM DEVICE_TYPE WHERE ID = ? [23503-197]

[Remotec ZRC-90 Scene Master]

I've answered my own question. I forgot one more remote that was still using the custom driver, so presumably what that error message means is "this driver is currently in use by device X so you can't delete it". Shame it couldn't say that rather than looking like I'd tried to hack into GCHQ!

Anyway all OK now.