You can't delete your old posts - they form part of our archive, and they can be useful to other people with similar questions to yours. You can view all of your past posts if you click on the three horizontal white bars at the left in the red PC Advisor bar along the top of the forum pages. Click on your username in the drop down menu and you'll see them listed.
Your username (marie-anna88) appears automatically at the top of each post you make.
You can't register with us unless you provide an email address, and you did that - I can see your address on my screen, but nobody else can. Do not add your email address to any of your posts - it's a bad idea to do that in a public web forum.
Your password is known to you, and to us. Nobody else can see it.