Shop manual does not specify draining the block, only the radiator.
There is a cut-out opening in the underbody cover underneath the radiator. Reach through to turn the drain plug and allow coolant to drain into a catch pan. Crack the radiator cap to enable venting.
Remove/clean the reservoir and refill radiaotor and reservoir w/ fresh mixed antifreeze coolant.
Start engine w/ radiator cap loosely and warm engine (fans come on). Turn off engine, check coolant level, top up, and tighten radiator cap.