You can add the following user roles to your Reseller account: 

Reseller Admins (added at reseller level): Have access to all business/locations under reseller account

Reseller admins are added under the All Users menu found in the upper right corner admin menu:

Business Admins (added to specific business/es): Can only access business(es) they are assigned to, and will have access to all locations for that business. Business admins can perform all functions for that business, and can add other business admins or business users.

Business Users (added to specific business/es): Can ONLY send review requests and view dashboard data, can't edit campaigns/add review sites/add other users.

Business admins and users can be added under the Business User menu found here: