tips or suggestions to remove cast iron trap

[bbxrider]

the pic kinda says it all, I want to remove the old trap and preserve the galvy connection and drain nipple side to attach a new temporary abs trap right now, the existing drain I will eventually completely replace when rebuilding the shower that it services but that is a little ways off.
I was hoping I can just break it apart with my 5lb hammer, thinking it may be still be attached/in place where it threads on but with most if it gone I can get a stillson on what remains and unscrew it from both the drain stub and galvy side. Trying to avoid cutting it off but I suppose I always have that option. been treating it with my 'blaster' penetrating oil which hopefully will do its magic yet again
if anybody has suggestions I would appreciate

 

[Geofd]

I would just cut it behind the threads and use a 2 band or 4 band stainless jacketed coupling and move that strap hanger back

 

[frodo]

you need a sawzall and a metal blade