The jetways in Aerosoft's BIKF are static jetways that are part of a larger scenery library bgl, so they can't be excluded with the GSX utility, nor can the entire library bgl file be excluded without also losing major parts of the scenery.
You have to use a utility like ModelConverterX to remove the KefX_Jetways_A, KefX_Jetways_B, and KefX_Jetways_C scenery objects from the library file (BIKF_Objects-LIB_1.bgl), which will leave you with the jetway bridge stubs in place (they are part of the terminal models). You can then place jetways onto the ends of those bridge stubs using GSX2.
Regards
Bob Scott