TL;DR: Send an email to firstname.lastname@example.org from the email associated with the account you want removed. Please note which POD provider you want us to remove the account from solid.community and/or inrupt.net).
As we’re rapidly working to emerge from prototype status, there are a number of regular use capabilities that we’re just beginning to incorporate into the system. The ability for a user to delete their own account is one of those things. This is a work in progress, and it will soon be merged into a new release that will enable it. Until that is in place, you can send an email to email@example.com from the email that you created the account with.