I'm trying to use the tool "delete ring" in order to create a hole in a polygon. The geometry of the hole is another feature of the same shapefile
I cannot manage to delete the part of the polygone. Does someone have a tutorial or some explanation?
You should be using
"Add Ring" tool to create a hole in the polygon.
Just Select the "Add Ring" tool and digitize a hole inside the polygon. It will remove that part and create a hole.