can you look at this question?
This has been discussed and answered already: future GSX version might add support for remove deicing pads, but it's not there, and it won't be enough to just add support for it in GSX, it must also being supported by the scenery, otherwise how GSX can't possibly know WHERE you are supposed to deice ?
You can have some kind of a workaround, to simulate this:
1) You must edit the AFCAD to add a new parking spot in the remote deicing area
2) Start from your normal parking, select Pushback and say you don't want de-icers. Use pushback to get out of there and turn the engines on.
3) After pushback, taxi to the new parking and park there. Set parking brakes on, and turn engines off.
4) Call GSX and choose Pushback and departure again, this time say YES to de-icing, then proceed out of there.
That's more or less a remote deicing simulation...