To delete a work from your profile, first go to your profile page. Click on the "Works" tab. In the upper right corner of the thumbnail for the work you want to delete, click Edit > Delete.

 

To delete a work published to a brief, first go to the brief page, click "View My Submissions" in the upper right corner, click on your submission, and in the pop-up window that appears, click on the "Options" tab in the upper left corner of your submission and click Delete.