How do I change my logon ID from google to zoho?

How do I change my logon ID from google to zoho?

I tried editing my logon email id to be from me@gmail.com to me@zoho.com, and when I clicked on "OK", nothing happened.

Also, I can't seem to add a secondary email ID.

What gives?  I just want to switch my primary ID from google to zoho, so that when I switch over completely, I won't have any ties left with the Big G.  Now that is not looking so likely.  Am I missing something that should be obvious?