There's really not much you can do except cut them apart. One of the reasons why epoxy is used on high stress critical areas is because of the tough a hold it does have. There is one thing you can try first, but I'm not making any promises as it usually doesn't work more often than it does. You can try heat to seperate the parts. Use a heat gun to heat the epoxy joining the parts. It will take time, so don't get in a hurry. If/when the epoxy starts to soften you can slowly work your parts apart.

If the heat doesn't work you're only other option is to cut them apart.

Ken