Why don't you change your plan to basic Simple Choice with 2GB of high speed data Included?
Not sure if there is a way to remove "data service completely" with simple choice plans. You'd need to get some sort of prepaid plan.
But to answer your question, Your Data Stash would be gone if you change plans.
^^^ This is a good suggestion. Since the 2GB feature is included in the plan, there's no way to take it off. The good thing about this feature is it doesn't cost you anything to have it.