Cancellation Letters are written by organization or individuals to cancel an offer, an agreement, a pre planned event, a credit account, a service, an order, a contract etc. for various reasons. Normally, all cancellation letters for business purposes follow the general format for any business correspondence. The following things need to be kept in mind while writing a cancellation letter.
Always use official letter head for such letters. Begin the letter with addressing it with the correct authority, state politely but unambiguously that you want to cancel the order/agreement/credit account /deal etc. The choice of citing a reason for the act is completely up to you. It depends upon what you are cancelling or after properly assessing the repercussions of this cancellation.
If there is a case of giving them a notice period then mention the date starting the notice period clearly. If there are some pending financial transactions or any other transaction of commercial nature that may be caused by the cancellation of this order then request them to be settled at the earliest possible date.
Undersign the cancellation order by the authorized personnel is necessary. Also, make sure there is an acknowledgement receipt on delivery of the letter or the mail.