deleteBuilds.gvy

Jenkins.instance.getItem("projectName").items.each {

  it.setDisabled(true)

  try {
    build = it.getLastBuild()

    while (build != null) {
      previousBuild = build.previousBuild

      println("deleting ${build.fullDisplayName} (${build.number})")

      try {
        build.deleteArtifacts()
        build.delete()
      }
      catch (Exception ex) {
        println(ex)
      }

      build = previousBuild
    }
  }
  finally {
    it.setDisabled(false)
  }

}