Within Teamwork.com, you can expand and collapse subtasks depending on whether you want them to be visible.
A parent task that has subtasks attached will have a number beside it denoting how many active subtasks it has.
In List view, click this number to the left of the task name to expand the corresponding subtasks. Clicking the subtask count again will hide the subtasks.
If a task does not have any existing subtasks, you can also access the subtasks view by clicking the subtasks icon to the right of the task name.
In Table view, hover over the relevant parent task and click the subtasks icon that appears to the right of the task name to display the subtasks. Clicking the icon again will collapse the parent and hide the subtasks.
Note: The subtasks icon is only visible in Table view on tasks with existing subtasks.
For more information, see: Collapsing and Expanding Task Lists