Oh no! It pains us to see you go. You may refer below steps!

Using ShopBack web:

Kindly submit your email address here, and you will be unsubscribed in 3-5 days.

Using ShopBack app:

Go to Account, scroll down to the bottom, and tap on Newsletter & Deal Info as per screenshot below:

Once tapped on Newsletter & Deal Info, you may choose to receive or not receive it by tapping on the slider bar: