How is coffee decaffeinated?

I presume someone will tell how the professionals do it. So, I will tell you how I do it!

Caffeine is soluble in hot water – very much like sugar. A typical cup of coffee has 100mg of caffeine. My drip coffee maker makes about 8 cups at a time and has a sneak-a-cup feature. That means there are about 800 mg of caffeine in the pot if I let it all finish draining and mix well.
But I don’t. (of course)
In the morning when I want more caffeine, I will sneak a cup when the machine has been dripping for a minute or two. That first cup has extra caffeine that has washed out. The remaining cups are therefore lower in caffeine. If I want totally decaf after the pot is empty, I pour water over the old grounds and drink that.
Presto! Decaf! And it was free!
I am not picky about flavor. I mostly want the hot water.

You can run the experiment yourself by mixing 1 gram of sugar crystals in with the coffee and tasting it as it drips out. The first cup will be much sweeter than the last.

There are four ways:

Swiss water process.
Super critical carbon dioxide.
Direct solvent.
Indirect solvent.

Read. https://sipcoffeehouse.com/how-is-coffee-decaffeinated/

^^Thanks so much jellies! The decaf coffee in the restaurant where my friend and I had breakfast earlier tasted so badly compared to the caffeinated one.