Only an Admin user has the permission to delete the account.
You can choose to delete your account by clicking on Settings from the top menu.
Scroll down to the bottom to find Delete Account button (highlighted below).
After clicking on the button, you'll get a popup message warning you that all data associated with the account will be deleted and none of the users of this account will be able to log in. If you agree to this, click on "Yes! I want to delete my account." and your account will be deleted.