You are not supposed to use ADE to remove jetways in a scenery, use the GSX Control Panel in combination with an Exclude file created by the GSX parking editor.
If a parking is not specifically flagged with an Exclude mark, no GSX jetways will appear. And, if you remove them from the original scenery with ADE, GSX cannot find their coordinates to replace them.
Basically, just follow the manual and the video tutorial posted here, there's no need to edit the original scenery.