No. Logging out and never logging in again is an option.
But I have never known a single site owner who will not rig an account, if they will not delete it, such that the original owner or anyone else can ever access it again. That's what was done on several other sites I was previously associated with for long periods of time. Accounts were never deleted, nor content removed, because forums serve as a historical record and if you (the generic you) posted it then it stays.
For places like this, that makes perfect sense. For most places, that makes perfect sense. Even if stuff were to be deleted, much can be found via the Wayback Machine.