Just to add to what the others have said, the reason accounts cannot be deleted is because they're shared across multiple CBS websites, such as TV.com and MP3.com (GameFAQs is also included in that bundle, but the account there is entirely separate from your GameSpot account) -- all of which had the same framework as GameSpot at one time, thus linking the accounts together to a certain extent. This means that your account is logged on multiple servers, which would cause all sorts of trouble should an account be removed from one server.
As fabz stated, you can just change your password to something you'll never remember and then log out if you wish to abandon your current account in favor of a new one.
The problem about not being able to delete an account has been shared for years now, but I think there might be some updates in the past 2 years that have said otherwise when users contact our customer support. To give you a little background about this problem, when we tried deleting accounts tons of content around the site remained on the site, including the blog content, but not the profile. When other users would re-register with the same account name (once deleted) they would find that they had content that wasn't theirs around the site (including user reviews and forum posts). The newly registered account would also encounter problems when posting in the game boards (that already had the username), along with other technical issues due to the formerly deleted account).
Long story short, there is a way to request an account deletion as long as the account has not been severely abused. If the account has been severely abused (numerous moderations or a permanent ban) or if there are associate accounts that were abused, the account deletion request is not accepted because we need to keep track of abusers who will likely cause the same abuse once they re-register with the same username (clearing their moderation history abuse). Plus, those who got a bad reputation on the site under that username might end up being accused as the original abuser, which would often lead to confusion on the site.
The last I heard, the deletion problem needed some more testing required for a fix. However, the help page has been available for quite some time now about how to request an account deletion via the customer support form. Take a look at it, and if you are eligible (no severe moderations that we need to keep tabs on) you'll be on the list once the deletion tool gets fixed.
I hope this clarifies the problem a bit more about why others are sharing there is no way to delete an account because there really isn't any way at this time. Thanks!