I have some question about images in K2

When I add some ilustration to article image goes to /media/k2/items/src/ and then there is created many versions in /media/k2/items/casche/

Could I stop that? My casche folder is 1.1 GB .

Unfortunately no,
This is how K2 works.

You can choose to upload the image through an extrafield.
There are several posts with example in this forum.

Could You give me some that posts?

It's impossible without changing core files.
You can just change in Settings unused dimension to 1px - the cache files will be much smaller.

The newly generated files will be much smaller indeed.