You would only delete any Asobo hand-crafted airports when replacing them with pay-ware. There shouldn’t be any issues with non-handcrafted airports since the basis for customization is to always overwrite the default airport. IOW, only when Asobo and a third party developer both create custom scenery for the same airport is there a possibility of strange behavior due to conflicts. Some installers are now deleting the Asobo customized airports, but it always pays to check since that doesn’t always happen. Also, there can be issues with conflicts in the community folder affecting pay-ware airports in strange ways even when the conflicts do not actually involve the pay-ware airport. I had issues with the scenery for Key West not loading due to conflicting file names with two free-ware add-ons that were in my community folder.