how do I delete a topic I started in the forums?

[Alwin Alcott]

as soon there are replies with quotes it's impossible, only a mod can do it than

[Alwin Alcott]

as soon there are replies with quotes it's impossible, only a mod can do it than

[Rolig Loon]

This is a public forum.  That means that as soon as anyone replies, your original post is no longer yours exclusively, so you cannot delete it.  You can edit it, but it's considered bad form to edit it by deleting your original text.  After all, even if you have learned all you can from the replies, other people may still benefit from the discussion.