Yes, you can edit an active promo code which is not used by anyone(registrant).
Step 1: Click on Edit icon of the Promo Code.
Step 2: Opens the Spend more Save more Promo Code in Edit mode.
Step 3: Click on ‘Save’ button to save the changed Multi-Item Discount Promo Code.
Click on ‘Cancel’ button to exit Promo Code screen without saving.