How can I remove something from my iTunes download list permanently?

Same as title: how can I remove something from my download list FOREVA! Why would I want to do this? Because it's a piece of poo free sampler from Best Buy that is effing huge, and terrible and I don't want it, ever (it's been stuck to my list since 08, and it must die). Every time I buy something I have to remember to go and remove that from my list, otherwise iTunes gets caught up downloading that thing, which is many times larger than any video/cd/app that I have ever downloaded on iTunes before. It wouldn't be as much an issue if I had a good ISP but I don't, so any non-apple employee people giving some smarmy "get better internets" advice need not apply.