The usual reason users want their accounts deleted is because they no longer want to get emails from JavaRanch. However there is no need to delete an account just for this. Just click on "My Profile", and edit the part that says can JavaRanch send you email to no. (or just set all the email stuff to no)
Not wishing the user name to be displayed publicly
If someone used their real name for their account, it can happen that some time later they no longer want it to be displayed in public, since it can easily be found using search engines. In that case just change it to some fictional -although real-sounding- name. This can also be done under "My Profile". In some ways, it's too late by the time you are asking anyway - assorted caches around the web already have the original.
Why can't you delete my account?
The forum software does not provide the facility to delete accounts - this would have to be added.
One of the main reasons JavaRanch exists is so that people can learn, and one of the ways to learn is by reading past posts. So even though your account may not have value to you, the posts associated with your account may still have value to the greater community.
From our perspective, the bigger question is: what should happen to your posts once your account is deleted?
If every post you have ever made was in a topic that you created, then we could go against the aims of JavaRanch and delete the topics you created - at a loss to the community in general.
However if you have created posts in topics that others have created, then it becomes far harder: if we delete your posts then replies to your posts may make no sense.
An option would be to reassign your posts to an account named "ex-user". However even this is sub-optimal as many members refer to users by name in their replies, especially if they are responding to 2 or 3 posts in a single topic. So even if your account didn't exist, your name could still appear in topics. For some (many) people this would be worse than if their original account existed. Imagine if your account was reassigned to "ex-user" but because your name was used in a response to your topic, it was still searchable through Google. So someone comes and looks at that topic. They see your message, and potentially 3 or 4 posts further down they see a totally ridiculous response by another "ex-user". Now they might associate you with that ridiculous response.
The end result is that there does not appear to be an automatic way of removing all traces of a user from our system. And if it is not automatic, then it is not likely to be done (as an example, imagine if I were to leave: could you imagine asking a volunteer to go through 1000+ posts and determine what can be deleted totally and what needs to be edited - I cannot imagine a single volunteer who would agree to that (and 1000 posts is not unusual - there are users with more than 10,000 posts)).
Farmers know to never drive a tractor near a honey locust tree. But a tiny ad is okay: