Uninstallation should be started only after disabling all the dependencies between custom objects and Intelligent Decision Dimensions add-on objects.
All the custom classes and reports should be redefined (or deleted) so that no /SKYBFR/YCA1 or /SKYBFR/YAI1 objects are used as dependencies.
Where-used list for /SKYBFR/YCA1 or /SKYBFR/YAI1 objects shouldn’t link to any custom objects.