After you have created a coupon you are able to edit it at any time. Simply click on content and select "coupons" there. Now you see an overview of all the coupons of this eventbaxx.
You will find two icons on the right:
To edit the coupon, click on the pen icon. You will be directed to the creation mask of the eventbaxx and can simply edit the things you did not like:
If you want to create a new coupon read more about further steps here.
If you do not need the coupon any more, use the red garbage can icon. The coupon will be deleted directly.
If you do not want to to delete the coupon but change its position read this short article.