To remove a merchant alert (and to discontinue the merchant alert emails/notifications), you will need to go to your name at the top right corner of your web browser when logged into your Abenity account. From there, you can select "Merchant Alerts".
This page will show the merchants you have selected to receive alerts for. You can de-select the highlighted blue "bell" shaped icon under the merchant's name. Once this has been de-selected, the merchant will be removed from your "Alerts" section and you will no longer receive alert emails from that merchant.