Pausing and Canceling Tasks
The Task window lets you pause, resume, and cancel tasks.
To pause a task:

Drag the appropriate task from the Active Tasks pane to the Paused Tasks pane.
To pause all tasks:

Choose
Pause All from the Task window menu.
To resume a task:

Drag a task from the Paused Tasks pane to the Active Tasks pane. The task returns to its previous position in the queue.
To resume all paused tasks:

Select
Resume All from the Task window menu. All tasks in the Paused Tasks pane (except failed tasks) are moved to the Active Tasks pane.
To cancel a task:
1. Highlight any task in either pane of the Task window.
2. Press Delete to remove it from the Task window.
To cancel all tasks:
1. Select any single task in either pane.
2. Press Command+A (Mac) Control+A (Windows) to select all the tasks in that pane.
3. Press Delete.
This command cannot be undone.