I want to change my 2-step verification to e-mail.
When I tried to change my 2-step verification from SMS to email address, I had to delete my SMS registration first to proceed, so I deleted my SMS registration, but the message "The email address you selected is invalid" was displayed.
When I tried to change my 2-step verification back to SMS, I entered the same phone number as before, but the message "The phone number you entered is invalid.
I do not want to register with the authentication application.
The best I can do is register with my email address, and the next best I can do is to re-register my phone number.