There are two common scenarios here:
Re-assigning a task with a single assignee
Re-assigning a task with multiple assignees
Note: To re-assign a task, you need to be the owner of the task you want to reassign.
Re-assigning a task with a single assignee
To re-assign a task with a single assignee:
Open a task.
Select the Assignee box in the upper left corner.
3. When the Edit/Change assignees dialog box opens, select Replace.
Note: When you change the assignee from a task’s main screen, it will change the assignee(s) in the Task Tree tab as well.
Re-assigning a task with multiple assignees
To re-assign a task with multiple assignees:
Open a task.
Select the main task in the Task Tree tab and Assignee.
3. Follow the same steps as explained above.
Note: You can remove an assignee only if they have not created any sub-tasks.