I don't know how to completely delete an account but to disable it you go to 'settings', then you will see 'disable my profile'.
To get rid of an extra account on your main one that you don't want, you need to export it to another email address. Just click on your name up top, open up the drop down menu, click add profile, scroll down and you will see where you can choose the unwanted profile and send it to another email address. That will cost you 25 rays though.
If what you want is to completely get rid of the account, someone else may be able to tell you. Hope this helps