How to delete a account

I have a account that has many registered products ranging back ~20 years.  Problem number one is that I am losing the email address associated with that account soon, and want change it to a new one.  Problem number two is that when I try to change the email address to my other email account, I discovered that an account already exists with that email address (which has no registered products) - I must have at some point created it and never used it.  So now am in a bind unless I can delete that account with no registered products so I can change the one I do use to that email address.
Any suggestions are most welcome.