You do not have to give your approval to be appointed executor of a will (although it is clearly polite to be asked). When the person dies, you a) make sure you take absolutely no action in the estate and b) renounce your appointment. That will mean the estate will effectively be left without an executor (if you are the sole exec) and the next person in line to extract the grant and administer the assets will be the residuary beneficiary/ies. As long as you take no action in the estate (known as intermeddling) you cannot be forced to act.