How do you delete the whole map in Minecraft?

So that there are no more blocks

It's not that easy.

If you want to have an empty map, you can simply create a flat world and select the setting "Empty" under the default settings for the flat world. Then you have an empty map.

But there must be a coman

You could do / fill air with the greatest possible range of coordinates. You still have to repeat this very often if you really want to have the entire map empty.