Once you are on the Dashboard, click on the Yearbooks tab on the left. Find the yearbook that you want to edit, then click on the down arrow to the right of the green Yearbook button. Click on Delete Element from the dropdown that appears.
If you have more then one element for that PLIC project, it will only delete that element. If you only have the one element for that PLIC project, it will delete the project from PLIC as well.