In this documentation, we can check how to manage promo coupon codes in Magento.
1) Login to Magento admin panel.
2) Go to ‘Promotions’.
3) Click the option ‘Shopping Cart Price Rules’.
4) Click the tab ‘Add New Rule’.
5) Enter the details.
6) Click the button ‘Save’.
7) If you want to delete the rule, click the button ‘Delete’.
That is how we can manage promo coupon codes in Magento.
If you need any further help please reach our support department.