When you’re viewing a Task record, the Send button will send the Task to the assigned app user.  They will receive it on their mobile device, to prompt them to do whatever you’ve specified.

You cannot send a Task until you specify one or more Activities for the Task.

Once you send a Task, the Task fields will be locked and no longer editable – though this may change in future versions.

The Delete button is always available and allows you to remove a Task at any time.

This will permanently delete the Task and its Activities, so take care when doing so.