If I may extrapolate a bit, I suspect that TiredOfBeingHuman's desire for deleting the account as opposed to simply not logging in is so that no trace of him having been on the site, in the form of his older posts and PMS, remains; he does not want there to be any remnants of him being associated with this website. As others have mentioned, though, the framework for the website does not allow such posts to be deleted--I am not very website-savvy, so I cannot spell out the dynamics too well, but it would basically mess up the coding and format of the website if prior posts were pulled from the threads and if users were pulled from the server (I think this has something to do with the numbering system attached to users/profiles?).
Mostly, though, I'm just posting to say how much I absolutely love your username. Best of luck and happiness in your outside life!
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I am not a textbook case of any particular disorder; I am an abstract, poetic portrayal of neurovariance with which much artistic license was taken.