There is only one reason why we will removed messages from existing threads: Privacy concerns
Webmaster will remove any information (privacy breach) from a forum messages that have replies.
If your message have no replies, you can edit it yourself without help from webmaster, you can edit and remove any info that you do not wish to keep online.
If you published online any information that could breach your privacy, like your real name, real address, your email address, your phone, or anything similar, or if you published any information about your diagnoses, and you are just one out of 5 people in the world with the same diagnoses, in that case you can provide a link to your message, and any private information will be removed from your message.
To edit any of your messages, click on the message title, and look for edit buttons at the header of the message.
In any case, if you need any help from me, you have to provide a link to any message you need help with.
To change the username shown on your forum messages, you can use this tool: