If a room only discount is announced and if your resort and room category are available for the discount, then the CM will simply apply the discount to the cost of your room. You do not have to change your package. The only thing that will be changed is how much you will be charged for the room portion of the package. It is very easy.
ETA: If your room type is not available for a discount and you want to book a different resort, then they can do that very easily. If your current reservation truly is a package and you want to switch to a room only reservation, then they will cancel the package, refund your money, then charge a new deposit. Again, it is easy. The CM handles these all the time.
Are you sure you have a package for you don't have tickets? A package reservation number begins with a letter whereas a room only reservation begins with a number.