Be able to delete the email you used to create your Proton account.

To create a Proton account they ask you for an email and in my case I used my personal Microsoft email, today and having a Proton email, I can not completely unlink the Microsoft email and I can also use it to log in to Proton.

It would be nice if they could give you the ability to completely unlink the external email you used to create your Proton account, so you can no longer use it to log in to Proton and you can no longer see it as external in "Identity and Addresses".