Allow user to change logged in account for Google API Authorization

I'm developing an analytics dashboard using GA data. I want to provide an option for the user to change the current user account from which the data is being pulled in.

Current Flow:

1. User lands on page


2. Is prompted to authorize the application


3. After authorization, the dashboard displays google analytic views

Desired Flow:

1. Same as above


2. Same as above


3. Same as above


4. User can click on a button, that allows a username/password field to change logged in account.


5. On submit, the new account is used to show analytic views.