I have a ton of projects in Eclipse Package Explorer and I want most of them to go away. How do I delete projects from the Package Explorer view (but keep the files)?
Just close the projects. Right-click on the top-level node of the project and select "Close Project". That's assuming you want to be able to use the project later. If you don't, you can delete the project - it will offer you the option of whether or not to delete the content files.
You might also consider using several different workspaces, each containing a few related projects.