P.S.: there is a small bug that I noticed in submissions view:
I deleted a submission record, but there is still shown 1 submission in forms drop down menu on submissions view page, but the Trash button is not visible here, so it is not possible to empty the trashed record.
I manage to empty trash this way:
I went to form edit, clicked submissions, et voilá, trash link was visible now. I was able to permanently delete the trashed record this way.
But as mentioned, when you go to the regular submissions view, trash button does not come up – also not after selecting the form.