changing a login name

While playing around trying to learn how to use ZOHO CRM I made two accounts for myself (using two different log ins and e mails) so I could understand how assigning tasks etc works.

Now that I am comfortable with it, I'd like to eleiminate one of those accounts and instead sign up one of my employees who will help me role out the software. I am able to edit everything about the user except the ZOHO CRM ID. How do I do that? I want to, in effect, delete one of the three current users and create a new one.

The HELP page only tells me how to do this for my fourth user and beyond.

thanks

~Fortunat