How do I edit the (runtime) classpath in Eclipse?

Question

In Eclipse, while trying to start Tomcat, I am getting this error:

The project: xxxxxxs which is referenced by the classpath, does not exist.

The reason is, I renamed my project from xxxxxxs to xxxxxx (note no "s"). It is still referencing the old one. Where is the (runtime) classpath and how do I edit it?

I know this is simple, and I've looked.

(Similar to Java Eclipse - How do I change the classpath? but I just want to know how to edit it, not how to solve my particular problem.)

Answer 1

Found it now that I've asked:

Run -> Run Configurations... -> Classpath

This is for the runtime classpath, for build classpath editing, see Java - Problem with the classpath on Eclipse.