Supplier Registration - Redwood - editing "What roles does this user need?" options

Summary:

Supplier Registration - Redwood - editing "What roles does this user need?" options

Content (please ensure you mask any confidential information):

On the "Configure Procurement Business Function" Setup and Maintenance Task under Procurement, we can configure Supplier Registration URLs:

I have completed the setup to enable Supplier Registration using Redwood pages, as per this feature:

Redwood: Next Generation User Experience for Supplier Registration

I want to control the list of roles available on the "Contacts" section of the registration:

Ideally, we don't want users to have access to be able to select any roles - e.g. it'd be useful to hard-code the "Does this contact need a user account?" to "No" and set that field to read-only.