Just my humble opinion but I think that it's okay to delete it...

Just my humble opinion but I think that it's okay to delete it given that it would only start from open tomorrow. Whereas if the tip had already commenced, that would be poor form. It's what you would do if you were really going to put money on it - if you get information after making the decision to buy (or shortsell in your case), but before actually putting your order in, you wouldn't go ahead with that decision if it no longer made sense to do so. Whereas if your order has been actioned and it's a dud, you're stuck with it.