Managers cannot delete tasks or check-ins within a workflow. They can, however, skip these activities.
New hires cannot delete items, but they DO have the ability to skip activities as well.
Skipping an activity will stop the activity from being delivered to the recipient. If the activity was already delivered, skipping the activity removes it from the workflow.
The recipient may see the task or check-in within a past delivered email but they will no longer see it within their ToDo list, their Calendar or within future emails that will go out. The recipient will no longer be responsible for completing the activity.
You can find further information on how to Skip and activity here.