You can delete critical tasks that aren’t absolutely required to meet your project goals. When you delete critical tasks, you will probably see an immediate effect: the project ends earlier. In addition, you may free up resources that you can assign to more urgent tasks in your project or to other projects.
When you delete a task that is linked to both its predecessor and successor tasks with finish-to-start (FS) links, Microsoft Project automatically links its predecessor task to its successor task with an FS link (by default). If you delete a task with any other type of link, you need to link its predecessor to its successor manually after you delete the task.
To delete a critical task
.