Flushing coolant 2014 Pathy

[ekanson]

Hi all. I recently got me a used pathy. Been doing some routine maintenance and noticed the required coolant is the blue stuff but my car has green antifreeze in the system. I want to flush the system with distilled water a couple of times and then add the blue extended life antifreeze. In the service manual, a water drain plug is to be removed in addition to the radiator drain plug. Anyone know where to locate the water drain plug? And will it be ok not to remove block heater before adding the 50-50 coolant?
Thanks