Coolant water, how can I drain it and put it back?

Hello,

The easiest way to drain the cooling system is to raise the vehicle in front so that you can access the drain plug. Fit a clean rubber pipe or similar to the drain pipe.
Loosen the drain plug and drain the coolant into a clean container
Once fully drained remove the old drain plug and fit a new one.
Refill the cooling system with the recovered coolant.

A good video:
https://youtu.be/5o6UYo-WfDs?si=B7TriQDhT7Bpsxf5

How to drain and fill:
https://www.2carpros.com/articles/coolant-flush-and-refill-all-cars

Cheers, Boris