Discover credit card allows you to prevent in store purchases by deactivating your card temporarily using online and with mobile app.
Temporarily deactivate(freeze) your card means Discover will not authorize purchases for in-store purchases, but can be used online, over the phone and for automatic bill payments.
Here is how to Temporarily deactivate card using mobile app
1) Login to your Discover mobile app
2) Go to Home and Tap Activate & Manage Cards
3) Select the card
4) Tap Temporarily deactivate card
5) Tap Deactivate card
You can activate (unfreeze) your card to turn in store purchase back.