You cannot actually remove your own account, I've tried, and also requested it one time.
As stated above, after 6 months accounts seem to have been removed due to inactivity. This wasn't something that we saw a lot of until after they merged the servers and freed up some names from inactive accounts.
Although, there have been recent errors in the system where someone who actively plays can log in and find all toons have been erased, but the high chance is that it was due to them being hacked.
Even if you have been using the forums, the way they detect that you play frequently is by actually..well...logging into the game itself and onto the servers.
Server side info bounces back the data from the player and onto their systems.