Some inactive models (not attached to a device) cannot be deleted. I get a “Please remove all devices before destroying” error.
In addition, the code drop-down in the Blueprint includes dozens of Code that’s not in the IDE (my old Planner stuff). This is not an issue, I don’t use the old Planner anymore. I suggest deleting the old code from the server for Beta testers if the code (model) is not in the IDE.