If you have an account with multiple locations, but those locations don't cross-over or interact with each other, there is an option to hide additional locations from your employees (included in the Premium and Business subscriptions).
An admin for the account can access this option under the company settings page.
Scroll down to the Restrictions section and look for the option labeled Visibility of coworkers across locations.
When disabled as shown above, employees will only see coworkers who are assigned to the same location as they are. This applies to:
The list of employees under the coworkers tab
The coworkers field within shift details
Users an employee can start a conversation with
Employees listed on the full schedule
Keep in mind that any conversations created before the setting was disabled will still be accessible to employees.
Admins will also still be able to create a group conversation that includes all users on the account, so use caution when assigning conversations using the "Everyone" group.