I understand. Thank you! :)

... in the HTML-Code ... you can still read what the user has written

for example in http://www.duolingo.com/comment/899070

[textarea class="post-edit-box comment-box" style="width: 96%; height: 80px;" name="post-edit-box"] I am sorry everyone ... I'm grateful to you who accept * My apology right here -Clara [/textarea]

you have to delete this text and the user's name

.

... or the user just has to edit the text as

[deleted]

and not use the "Delete"-Command

But couldn't it be done in a way that doesn't show who posted the original comment? I think a lot of times people delete comments because they're embarrassed about something they posted. It doesn't do much to help that if your user name is still there. For instance, in a Spanish discussion I once asked a dumb question with an obvious answer that I was embarrassed about afterward, but it had already been answered so even after I deleted my comment people could see my username and deduce by the response what the question was. Not a huge deal, but it would be more courteous to users who occasionally do things that they're embarrassed of if this weren't the case. The same goes for discussions. I've seen people post discussions like language requests or other down-vote magnets and obviously regret them, but when they delete the content of the discussion, if it's been commented on, the post remains and continues to attract down-votes and negativity with their names still attached.