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

Eclipse menu -> Run -> Run Configurations... pops up the list of all viable run configurations, grouped by type. You are looking for those under Java Application. Any of these are deletable. Delete them and they will no longer show up in Run/Launch configuration lists.