Hi it is a limitation for the moment.
To remove only the di you have to disable the "Di view" filter in the Project Explorer view options.
In project Explorer View > arrow oriented to the bottom > Customize view > Uncheck DI view.
Ok now on the correct view: I can uncheck the "Di view" option.
Now, the di files are not agregated bellow a common parent.
But it doesn't resolve my problem : when I delete the ".di" file, the ".uml" is automatically removed!
Is there a way to remove the .di file only?
agregated : my firefox dictionary tells me to put 2 "g" to agregated like this "aggregated" and I see only one "g" in the description of the "Di view" option), probably a spelling error to report.
You can switch from the Papyrus perspective to another Eclipse perspective (e.g. Java perspective), and you should have no problem to delete only the .di file. This is obviously a trick, but I hope that this can help you.