How can I clean up Eclipse "run configurations"

Question

I set my java runtime options in Eclipse's Window > Prefs > Java > Installed JREs > Default VM Arguments. Since this setting is sufficient for all my main() entry points, I do not bother with customizing the "run configurations". It looks like nice flexibility but I probably will never need it. I was worried that I would have to repeat my VM arguments in the run configurations and so I started to copy my VM arguments but after an experiment it seems that I do not have to. Now I will have the opposite worry that I have some unintended customizations.

To eliminate the second worry, is there a way to eliminate the clutter visible in the Run drop down menu? What about the "Launch configurations" visible in the JAR export dialog? Is a run configuration the same thing as a launch configuration? How do I eliminate the multiple launch configurations?

I am on Eclipse Indigo on Ubuntu.

Edit After I manually delete all the run configurations, and proceed to do an export, buttons are greyed-out so I can't proceed. When I select the launch configuration drop-down, I end up with only one choice, from an unrelated project. I then created a run configuration for the real main entry point for the current project. I expect the clutter will return as I continue to use Eclipse.

Answer 1

One simple way would be to organize your projects by Eclipse workspace, which would limit the "run configurations" list only to the project referenced in a given workspace.
Switching workspaces would reset that list to the ones recorded for the projects of the new workspace.

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Note: the OP's answer regarding launches file location isn't the only location possible.
The official one is:

${WORKSPACE}/.metadata/.plugins/org.eclipse.debug.core/.launches

But you can copy them enywhere else you want (as explained in "How do I save Eclipse launch profiles across workspaces?"), either by manually copying those files or by sharing them:
See "Which eclipse files belong under Version Control".

Once you know where they are saved, a simple delete is enough to make them disappear from the launcher menu.