1. Click on "Coupons" under the Billing menu.
2. Choose the coupon you'd like to disable/discontinue and click on the 3 dot stack.
3. Click on "Disable Coupon". If you select this, existing members will keep their discount, but no new users will be able to use it.
4. If you are sure you want to delete the coupon, select "Yes, delete it!".