You cannot stop payment on a cashier's check.

More Info: Unlike a personal check, a cashier's check is purchased in advance with the funds being immediately transferred and held by the issuing bank.  So technically speaking, you can't stop an impending payment on an item that has already been paid for.

You can however, put in a claim for a lost, stolen, or destroyed cashier's check ninety days following its issuance.  If the check has not been presented in the timeframe the bank may issue a refund.  Be warned that a cashier's check can be presented after that date and if cashed, the bank will likely hold you responsible for the return of the refund.

How Do You Stop Payment on a Personal Check?

In order to stop payment on a personal check you have issued, you need to contact your financial institution. You begin by collecting all the relevant information. This includes your account number, the number on the check you will be requesting the stop payment on, the amount the check was written for, and the individual the check was issued to. Your financial institution may allow you to submit this information through their website, or may require you to contact them by telephone. The stop payment will prevent any transfer of funds that has not already occurred.

Can You Stop Payment on a Money Order?

Money orders can be drawn on a number of sources like banks and the USPS. Banks have rules and guidelines concerning money order stop payments. The USPS has some guidelines, but does not necessarily guarantee return of your funds. It is much easier and much more sensible to pay with a credit card or debit card. If this is not possible, consider the use of a cashier's check. Money orders are sometimes treated like non-refundable cash and should only be used in situations where you are relatively sure that no problems will appear in the future.