Confirmed user accounts persist indefinitely.

Message deletion requests are typically ignored; deleted posts may be undeleted at any time for any reason.

Even when deleted, messages continue to persist indefinitely - and may remain accessible to others; archives - delete doesn't mean gone.

On an aside, getting rid of computer data is extremely difficult - formatting, overwriting, etc rarely do much good ... even a low-level format often won't do it for various reasons, one of which being is that most all HDs will contain least some data left behind in "weak" sectors (there can be a lot of them) that have been mapped out at the hardware level.

Anyways, only sure way to erase data is to physically damage the media the data is on, be it a HD, memory card, RAM in some instances, etc.

In a nutshell, trying to erase the past is a futile effort at best - in fact by trying to erase it, one is likely to do the opposite by bring more attention to themself, what they wrote, etc.

Ron