You need to delete the project .prel file. Hopefully you created a project folder when you started your project. The .prel file and all associated project files (which can take up a huge amount of space) should be in this folder. default location for folder creation is in your My Documents folder under Adobe, Premiere Elements.
See this FAQ:
Hi Paul, thanks for the quick and useful answer. I found the default folder and removed the associated files. The unwanted projects under "recent projects' now no longer show up. I also found the auto-save files and deleted all but the last one. From here on I'll create a related folder for each new project. Thanks again. Barry