I don’t know if grapes are fumigated for european markets. In the US they are generally not fumigated, although they are fumigated with sulfur if they are going to be exported to Australia (required by the Australian government).
They aren’t fumigated in the field, it’s usually applied as a dust/powder.
Here’s a video of grapes being dusted with sulfur in India. The machines are different in different countries, but it looks pretty much the same wherever sulfur dusting is done. The dusting is done every 2-3 weeks during the summer and late spring.
Sulfur can also be applied as a liquid solution. That product is called micronized sulfur. This product is a little more expensive but more popular in the US because it is more comfortable. As you might imagine, applying sulfur as a dry powder is very irritating to the skin and eyes. But it still leaves sulfur residue on the fruit, so it doesn’t help from a consumer perspective.
Unfortunately I don’t have good advice for removing sulfur, I haven’t personally tried to do that. There are fruit and vegetable soap products that are safe to apply to food. I would recommend trying those, although I’m not sure if they will help very much.