I'm sorry to hear that you want to cancel your account. It would probably be best for you to click the "feedback" link in the top right corner and located to the right, beneath your Yedda online name.
To delete answers, just go into each answer and instead of clicking reply or edit, you may choose to delete the answer. To delete questions is a different animal all together. You may need to take that up with the company at the feedback link. They will direct you as to how you can delete your questions, if possible. Perhaps when your account is canceled the questions will be deleted as well.
I wish you the best with Heartbeat 120, and give my regards to Miley Cyrus when you see her.