Since that is a 3rd party airport, the GSX Control Panel doesn't have anything to do with it, since it only controls if *default* jetways at *default* airports are disabled.
So, those jetways are there because you placed them there with the GSX parking customization editor. Or, if you are using a customization made by somebody else, they were added by who made that customization, which can be either another user, or possibly the scenery developer himself.
Of course, if you said which scenery you are referring to, and which customization file you are using, it might be easier to help you.