I also joined the beta-program and have the same app and fw versions as ville. I can see the trash icon, and it does what it should.
“I think it removes them actually from the card on the mooshimeter.”
Yes, I can confirm that; just tried. However, the function seems new and still buggy – it lets the app kind of crash each time. A message like “Mooshimeter has just been terminated” appears (in german in my case). This behavior is reproducible, so after each deletion I need to reconnect. But the respective logfile is really deleted anyway.