I am 37 and I might be dumb but I am not stupid....
LOL!!! You are saying someone can be Dumb and Smart? Ok then...
In the future, if you want to avoid such responces, you really should be clear the first time on the issue you are having and the product you are using. You are in a FSDT forum asking for support for another developers product. As SirIsaac726 well stated, you were vague. We both could have simply ignored your post like everyone else. But obviously we are interested. Thus, don't bite the hands trying to help you in the future. We are happy to help you so long as Virtuali doesn't mind. If you are 37, act like it.
I had a similar issue in the past. Try this: Make sure there are no dup Afcad files. This really looks like an Afcad issue. Back up your [Addon Scenery] folder, then delete or remove the [scenery] folder from your FS tree. Also backup and delete the [scenery.dat] file in same folder. Restart FS, if the default builgings are gone, then the problem is in your [Addon Scenery + Scenery] folder. If they are still there, then you will have to remove all default airport buildings in that region which is not an issue if you never fly to default airports. I can tell you how to do that. Your last option will be a complete FS reinstall. Because I am such a nice guy, I will install the scenery myself to see if I have the issue.
Good Luck.