To eliminate a single design, go to your 'Entries' tab and click on the eliminate icon on any one of the designs of the designer you want to eliminate and select the 'Eliminate design' option. Follow the prompts to eliminate the design.
Sometimes you may feel that a particular is not upto the mark or is unable to provide you the designs that you are looking for, in such cases, you can either eliminate the designs that you don't like or simply eliminate the designer all together. Thus, preventing the designer from submitting any further designs in your contest.
Pro Tip: If you have eliminated a design by accident, you can reinstate it by clicking ‘Un-eliminate design’ button which will have replaced the ‘Eliminate design’ option in the same place. Keep in mind, the designer will still be able to submit more designs in the contest as you have only eliminated their one design. But always remember to give a feedback on why you are eliminating the design, it will help the designer to come up with something better.