This QScript snippet hides a question from the drop-downs and Data Sets pane. You can incorporate this into your own custom QScript.
Method
//get list of question
var questions = project.dataFiles[0].questions;
//prompt for which question to hide
var question = questions[selectOne('Which question to hide?', questions.map(function(q) {return q.name;}))];
//set to hidden
question.isHidden = true;