Everything went ok in the job, only once deleting the project workspace was getting an error. The files and the directory of C:\CMS\plugins\Login\conf was gone/deleted. So I don't understand this error.

I don't understand why I getting this error. I used the: Jenkins Workspace Cleanup Plugin

Deleting project workspace... ERROR: Publisher hudson.plugins.ws_cleanup.WsCleanup aborted due to exception
java.io.IOException: Unable to delete C:\CMS\plugins\Login - files in dir: [C:\CMS\plugins\Login\conf]
at hudson.Util.deleteFile(Util.java:236)
at hudson.Util.deleteRecursive(Util.java:287)
at hudson.FilePath$11.invoke(FilePath.java:900)
at hudson.FilePath$11.invoke(FilePath.java:898)
at hudson.FilePath.act(FilePath.java:832)
at hudson.FilePath.act(FilePath.java:814)
at hudson.FilePath.deleteRecursive(FilePath.java:898)
at hudson.plugins.ws_cleanup.WsCleanup.perform(WsCleanup.java:55)
at hudson.tasks.BuildStepMonitor$2.perform(BuildStepMonitor.java:27)
at hudson.model.AbstractBuild$AbstractRunner.perform(AbstractBuild.java:705)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:680)
at hudson.model.AbstractBuild$AbstractRunner.performAllBuildSteps(AbstractBuild.java:658)
at hudson.model.Build$RunnerImpl.cleanUp(Build.java:171)
at hudson.model.Run.run(Run.java:1465)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:46)
at hudson.model.ResourceController.execute(ResourceController.java:88)
at hudson.model.Executor.run(Executor.java:238)