Ability to remove a sign-in option

[nickbolton]

We allow users to add a different sign-in option after they have signed in. For example, if they originally signed in (and created an account) with phone, we allow them to add an email address that they could use later (and vice versa). We want the ability to remove any assigned sign-in options they might have initiated by the user and not part of a serice role function. Of course, they would need to maintain at least one.