Deleting a recurring assignment erases all future instances of the assignment and changes past detail assignments into non-recurring assignments. If you've entered an assignment incorrectly, deleting it is the best course of action. To do this, right-click on the recurring assignment and select Delete.
Cancelling the recurring assignment cancels all future assignments within it and does not affect past ones. To cancel the recurring assignment, click on it to open it, click on Cancel... then Cancel all.
Cancel for time period
Cancel for time period will prompt you for a date range and cancel all detail assignments between these dates. To do this, select the recurring assignment, click on it to open it, click on Cancel... then Cancel for time period.
Cancelling a single assignment (or shift)
To cancel a single assignment, open the recurring assignment then right-click on the detail assignment you want to modify and select Change Status.