Depending on your Organization's solution a Clear Schedule and/or a Clear Generation Method option should be available in order to delete all scheduled assignments on the roster for all employees at once.
This article will provide a walk-through of the first option (Clear Schedule).
1. Click on the Scheduling icon from the navigation menu.
2. Select the Roster option in the Schedule section.
3. Click on the Date Header.
4. From the action menu, select the Clear Option.
5. Select the Start/End dates for which the Schedule will be cleared.
6. Select the clearing Options.
7. Additionally, the Employee Criteria can be used in order to filter from a wide variety of entities (Employees, Groups, Base Schedules, etc.)
8. Press the Clear button.