I'll add to this in case anybody has any issues with default scenery showing in the future with OMDB, KLAX, EDDS or any other addon that replaces a default airport.
I have the premium-deluxe edition from MS:
When testing the scenery, it was sometimes necessary to delete the default Asobo airport 2 times.
For whatever reason, after the first uninstall and game restart, there would still be 50-100mb worth of scenery that wasn't removed and the old airport was showing through. Remove it a second time and it'll be gone for good.
Deleting the airport manually also did not help as it would re-install automatically when loading the sim again. Maybe this is because it was purchased from MS and not Steam, I'm not really sure.
One last note: After performing a sim update, sometimes it will reinstall the default scenery as it did with me a few weeks ago. Just repeat the removal process.