I renamed the AFCAD file in the scenery folder on mytrafficX as you suggest but the issue is still there
This means that wasn't the only AFCAD in conflict. As I've said, use the FSX Airport Scanner program to be sure there aren't any other.
There is no way to remove the default scenery below? I am convinced that the problem is that
No, it's not and, in fact, you shouldn't remove the default scenery, because the KORD AFCAD is *designed* to work together with it so, unless you modified it, they have to be both active.
Something like that might happen if you opened the default AFCAD with a non entirely compliant AFCAD editor (for example the old AFCAD utility for FS9), make some changes, and save it back. Doing this with the old AFCAD utility would create lots of issues.
If you haven't done anything of the sort, then it's sure there's another scenery in conflict. Of course, be sure the FSDT KORD layer in the Scenery Library is ABOVE any other layer that might contain conflicting sceneries. If unsure, just put it on the topmost layer.