Step 1 :
$ RAILS_ENV=production script/delayed_job stop
This will stop the delayed_job process.
Step 2 :
$ pgrep -f delayed_job
This will return no result, therefore confirming that the delayed_job process has been stopped.
Go to rails console in production and run :
> job = Delayed::Job.count
(0.3ms) SELECT COUNT(*) FROM `delayed_jobs`
> job = Delayed::Job.first
Delayed::Backend::ActiveRecord::Job Load (0.5ms) SELECT `delayed_jobs`.* FROM `delayed_jobs` LIMIT 1