Not that easy. The potting epoxies made for this purpose are nothing like your regular epoxies. They're pricey and when you try to break them you are very likely to tear the parts right off the board. This is the brand I have used in the past:
replyhttps://www.masterbond.com/techtips/tamper-resistant-potting...
The devices we made were put in places where there was a significant risk of tampering and to the best of my knowledge nobody ever managed to break the epoxy bond to the point that the circuit was still functional. But as I wrote above: not cheap.