Settings, Apps, Galaxy Store, Disable. It should revert it to the stock version and disable it. Unless your phone has some additional restrictions that prevents disabling it.
Or instead I can not spend all that time and effort messing with my phone that holds all of my data and instead but a moondrop phone and never show Samsung my wallet again.
You're actually buying that Moondrop device? Let me know how it goes, seemed like a cool concept but I can't trust them enough to get a mobile device done right