You cannot delete or modify a project summary task.}A project summary task summarizes your entire project. You can change ...

{You cannot delete or modify a project summary task.}A project summary task summarizes your entire project. You can change its wording, attach a note to it, and hide or show it; but you cannot delete it, link it to a task, assign non-budget resources to it, or perform other actions that you can only perform on summary tasks and subtasks.

To hide the project summary task, click Project Summary Task on the Format tab.