You can turn off the free job boards for an "Open" job posting. It will take 24 hours for the job posting to be removed from the free job boards.
Go to the Jobs tab.
Click on the appropriate job title.
Click on the "Job Boards" tab.
Click the empty green space.
The slider scale will be greyed out and the white cycle will be on the left hand side, which indicates that the job boards have been turned off.