Is it possible to choose where he has to cut off - like a lumberjack? 
Or do I have to create it by my own or is there any third party program that does for me? 
Take a look at this thread: https://forums.unrealengine/showthread.php?63683-Specific-part-in-a-Destructible-Mesh
Otherwise you could also use APEX -> I think there it should also be possible to do that 