XNALara

Maybe you can, but I'm not sure. I suggest you to first export the model, then import it back with the XNALara script and then remove the unused bones (when I do it I don't get any problems). Mind that some bones, apparently unused, are actually important for the functionality of some other part. Eg, let's say your head it's connected to a bone you don't want/need... if you delete them, then you have to of course reparent the head, but also to remove the vertex group assigned to the deleted bone (I don't know how to do that in Max, I use blender). So remove them only if you are totally sure that they don't move nothing and I also suggest you to make a copy of your exported model, in case you didn't.