How do you replace the ac compressor on Honda Odyssey?

You need to be certified to purge the system. Taking the compressor off is simple but you have to remove the refrigerant first.

WA can't tell you to do illegal things so I can't tell you to disconnect the lines after you have vented the refrigerant to atmosphere. I can tell you to be sure to wear safety glasses when you do it because it can frostbite your eyeballs.