Find the name of the job, this is usually in the URL - https://jenkins.domain.io/job/job-name-example/123
In this example URL the job name would be - job-name-example
Find the number of the job, this is usually in the URL - https://jenkins.domain.io/job/job-name-example/123
In this example URL the job number would be - 123
Navigate to the Script Console in Jenkins UI - https://jenkins.domain.io/script
Paste the following code block into the console and replace the JOB_NAME and JOB_NUMBER for the values you found in step 2 and 3.
Jenkins.instance.getItemByFullName("JOB_NAME").getBuildByNumber(JOB_NUMBER).finish(hudson.model.Result.ABORTED, new java.io.IOException("Manually aborting job via Script Console"));
Click Run
Check the job has been aborted by going back to the original job url - https://jenkins.domain.io/job/job-name-example/123