At any point, you can withdraw your designs from a contest by:
1. Go to the contest you want to withdraw the design from.
2. Click on the design you want to withdraw, as shown below.
2. Click on the 'Withdraw design' button, and the design will be removed from the contest, as shown below.
You can always re-submit a withdrawn design later if you change your mind. Also, if you would like to reuse a non-winning design in another contest, you are required to withdraw it prior to submitting to the new contest.