You cannot delete your account. You can stop logging in. If you want to lock yourself out forever you may ask a friend to change your password and then change the email to one of those throw-away ones and then you can’t get back on.
I suppose you could ask to be banned but all your posts would still remain and your account would still be searchable. There is no “Delete” function on a message board that would cover anything but “banable” offensive posts.
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