There's an automated process that confirms the request via email and starts a timer that, if not cancelled, removes the account. For accounts with a non-trivial number of posts we hold them for manual confirmation just to prevent unfortunate accidents (there's no undo - more on that next) but all it involves is an affirmative response from an email associated with the account.
The longer answer is... This is one of those very early design decisions that, in hindsight, was probably sub-optimal. Ideally, account deletion would amount to nothing more than flipping a bit on a database record, at least in the short term - if someone regretted their decision a day later, no harm done; just flip it back. But things are not ideal, and deleting an account actually purges rather a lot of information that can't easily be restored - so given that a non-trivial number of users do change their minds (especially those with a long history of activity that will be lost), it's worth everyone's time to make double-sure before hitting the big red button.
We've slowly been improving the process over the past few years, but it's still no where near ideal from anyone's perspective. I could go into more detail, but... Can sum it up with, "We're now only wasting ridiculous amounts of time on this instead of utterly insane amounts of time".
There's an automated process that confirms the request via email and starts a timer that, if not cancelled, removes the account. For accounts with a non-trivial number of posts we hold them for manual confirmation just to prevent unfortunate accidents (there's no undo - more on that next) but all it involves is an affirmative response from an email associated with the account.
The longer answer is... This is one of those very early design decisions that, in hindsight, was probably sub-optimal. Ideally, account deletion would amount to nothing more than flipping a bit on a database record, at least in the short term - if someone regretted their decision a day later, no harm done; just flip it back. But things are not ideal, and deleting an account actually purges rather a lot of information that can't easily be restored - so given that a non-trivial number of users do change their minds (especially those with a long history of activity that will be lost), it's worth everyone's time to make double-sure before hitting the big red button.
We've slowly been improving the process over the past few years, but it's still no where near ideal from anyone's perspective. I could go into more detail, but... Can sum it up with, "We're now only wasting ridiculous amounts of time on this instead of utterly insane amounts of time".