For non-supersymmetric models one can use the following two options in the Main Model File:
NoU1Mixing = True/False;, default: False, disables effects from gauge-kinetic mixing
IgnoreGaugeFixing=True/False;, default: False, disables the calculation of the gauge fixing and ghost terms. Note, that this should just be done if a model is studied at tree-level. For a correct calculation of the loop corrections, the ghosts are needed. More information about the gauge fixing terms and ghost interactions is given here.