Jenkins Remove All Builds

Go to Dashboard > Manage Jenkins > Script Console and use the following script to leave just last build

import jenkins.model.Jenkins
import hudson.model.Job

MAX_BUILDS = 1

for (job in Jenkins.instance.items) {
  println job.name

  def recent = job.builds.limit(MAX_BUILDS)

  for (build in job.builds) {
    if (!recent.contains(build)) {
      println "Preparing to delete: " + build
      build.delete()
    }
  }
}