How do I clear my Jenkins/Hudson build history?

If you want to clear the build history of MultiBranchProject (e.g. pipeline), go to your Jenkins home page → Manage Jenkins → Script Console and run the following script:

def projectName = "ProjectName"
def project = Jenkins.instance.getItem(projectName)
def jobs = project.getItems().each {
  def job = it
  job.getBuilds().each { it.delete() }
  job.nextBuildNumber = 1
  job.save()
}

This one is the best option available.

Jenkins.instance.getAllItems(AbstractProject.class).each {it -> Jenkins.instance.getItemByFullName(it.fullName).builds.findAll { it.number > 0 }.each { it.delete() } }

This code will delete all Jenkins Job build history.

Using Script Console.

In case the jobs are grouped it's possible to either give it a full name with forward slashes:

getItemByFullName("folder_name/job_name") 
job.getBuilds().each { it.delete() }
job.nextBuildNumber = 1
job.save()

or traverse the hierarchy like this:

def folder = Jenkins.instance.getItem("folder_name")
def job = folder.getItem("job_name")
job.getBuilds().each { it.delete() }
job.nextBuildNumber = 1
job.save()

Deleting directly from file system is not safe. You can run the below script to delete all builds from all jobs ( recursively ).

def numberOfBuildsToKeep = 10
Jenkins.instance.getAllItems(AbstractItem.class).each {
  if( it.class.toString() != "class com.cloudbees.hudson.plugins.folder.Folder" && it.class.toString() != "class org.jenkinsci.plugins.workflow.multibranch.WorkflowMultiBranchProject") {
    println it.name
    builds = it.getBuilds()
    for(int i = numberOfBuildsToKeep; i < builds.size(); i++) {
        builds.get(i).delete()
      println "Deleted" + builds.get(i)
    }
  }
}

Go to "Manage Jenkins" > "Script Console"

Run below:

def jobName = "build_name"  
def job = Jenkins.instance.getItem(jobName)  
job.getBuilds().each { it.delete() }  
job.save()

Tested on jenkins 2.293 over linux. It will remove all the build logs but not the corellative build number

cd /var/lib/jenkins/jobs
find . -name "builds" -exec rm -rf {} \;

Be careful with this command because it executes a rm -rf on each find result. You could exec this first to validate if the result are only the builds folder of you jobs

find . -name "builds"