It is now possible to copy and move tasks from task details and tasks pages. Delete operation is available from these pages too.
Task Details Page
To move or copy task, select the source sprint in the "In Sprints" list, select target sprint in the selector and click 'Move' or 'Copy' button. To delete a task from sprint, select the sprint in the "In Sprints" list and click 'Delete From Sprint'.
To move or copy select the tasks, select target sprint and click 'Move' or 'Copy' button. To delete, select the tasks and click 'Delete From Sprint' button.
Important! The source sprint for all these operations will be the first sprint in the "In Sprints" list for the task. In the example screenshot below, the source sprint will be 'Code Inspection' for task #12 and 'Backlog' for task #11.
Task Operations and Hierarchies
Copy operation will not copy any subtasks. To do that, go to the source sprint and copy the task hierarchy directly from there.
Move operation will move all subtasks from the source sprint (including subtasks of those subtasks).
Delete operation will delete all subtasks from the source sprint.