If the scenery has docking system made with SODE, there's no way you can disable it from GSX and there's no way GSX could affect it in any way. The only way to remove a SODE docking system, is by manually removing from the scenery SODE XML file.
If you press the Reset button, then Apply, GSX will Undo all the changes made to that parking spot. If you enabled the jetway Exclude radius, you'll also have to exit from the sim, go into the GSX Control Panel and let it update (or remove, if not needed), any exclude file which was generated for the scenery.