Support Administrator Role is not available when navigating to Setup > Users/Roles > Manage Roles.

The Support Administrator role is controlled by this feature Customer Support and Service found on the CRM tab via Enable Features page.

Here are the steps:
1. Login using the Administrator role.
2. Navigate to Setup > Company > Enable Features.
3. On the CRM tab, set Customer Support and Service box checked.
4. Click Save.

When user navigates to Setup > Users/Roles > Manage Roles > user should now be able to see the Support Administrator on the list of roles.

Note: If this feature is not available on the Enable Features page, contact the NetSuite Account Manager to purchase this feature.