How to remove launch configuration histories in eclipse?

Question

Right click an arbitrary existing project in Package Explore, choose \"export...\" - \"Java\" - \"Runnable JAR file\", I find all the old projects in the \"launch configuration\

Answer 1

Go to Run->Run configuration. Delete the existing saved projects under the Java Application.

Then run the class, having main method from eclipse. It will be automatically set.

Now create runnable Jar.