This article explains two ways to remove Samsung Pay: by clearing all saved credit and debit cards or by uninstalling the app.
How to Disable Samsung Pay or Samsung Pay mini Swipe Up Shortcut from Home Screen and Lock Screen
One way to disable Samsung Pay is to remove any credit or debit cards linked to your account. Samsung Pay will still be on your phone, but without valid cards to use, it won’t work as intended. You can always re-link your cards in the future if you need the service later.
Tap the three-stripe menu icon in the top left corner of the app.
Select a card and tap More options.