You can read about deleting things you have posted. You can also contact italki to request assistance to delete something. http://support.italki.com/hc/en-us/articles/206353318-Can-I-edit-or-delete-my-comments-on-Notebook-Answers-and-Discussions-after-posting- Click on "submit a request" (this will allow you to send an email)

Here is a better link (better than http://support.italki.com) http://support.italki.com/hc/en-us/articles/206353318-Can-I-edit-or-delete-my-comments-on-Notebook-Answers-and-Discussions-after-posting- Click on "submit a request" (this will allow you to send an email)

I suggest that you contact italki support. Tell them that you made a mistake and posted/wrote something that you would like to delete. http://support.italki.com

As I know, you can only delete the notebook written by yourself, others(comments, discusses, questions) not.

I don't think you can.. At least I can't find the option anywhere.