Topic: Can you cancel DLC pre-orders?

A friend of mine was playing Mario Kart 8 with me, and while I was out buying some snacks, he went ahead and downloaded the MK8 pre-order DLC pack. That was quite some time ago, and I never noticed until I saw it on the [Shop] section of the game, where it told me that I had purchased it! I was really confused, until my friend came over again and asked why he can't play as Link yet. Then he told me he thought I'd want it anyway, and he also offered me a 15€ eShop card, but that's definitely not what matters.
The thing is, I don't want that disgrace on my WiiU, or have it connected with my account at all. Call it childish, but that's none of your business. I genuinely care about the dignity of Link, and as such, don't wanna imply any support for Nintendo's recent cameo insanity.

So, to the question: is there any way to cancel the pre-order? It IS a pre-order, after all, and nothing's out yet. I don't really care for the money I lost, this is all about erasing the DLC from existance on my WiiU permanently.

Get in touch with Nintendo proper. Even if you are able to delete something from your device you'll still have it available for download via eShop, and since it seems to be such a big deal for you only Nintendo themselves are capable of making that sort of edit to your eShop account, if at all. Good luck to you!