You can cancel your pre-order as long as it is not yet in the shipping process.
Log in to your account. There you cancel the pre-order item on its own, or your whole order.
Did you only cancel the pre-order item? Then your order no longer has to wait for anything and we ship the rest within the usual processing time. Want to keep your pre-order and receive the items that are already in stock sooner? The best way is to place those as a separate order. If everything is already in one order, contact us: we will ship the in-stock items ahead, against payment of the extra shipping costs.
Is your pre-order already in the shipping process? Then we can no longer stop it. You can return the parcel after receiving it. How that works is explained in How do I register a return?