Go to https://www.careermine.com/employers/ and sign in.
Under the drop down click on My Job Postings
This will show you a list of your positions that you have previously posted or started.
If your job is still posted on the site it will give an option under Modify on the right side of the screen to either Edit and/or Unpost your posting. This page will also show you any previously posted jobs you may have had on CareerMine.
Simply select one of the Modify options and follow the onscreen instructions.