If you have your manual, it's on page 23. From the project helper you click on the little folder in the bottom left hand corner for 'Open a project not listed above'. That takes you to your PJ7 default folder where all your projects are saved on your computer. Right click on the old project and choose delete from the pop up menu. It'll ask you if you're sure you want to send the project to your recycle bin and click "yes". Boom.