how to remove whats left of o2 sensor?

[commercialfshrmn]

after they decided they needed the OEM cats more than i did, this is the rear driver side that i was left with. tried "everything" to get it out.......i need some help! this is what i was left with

https://imgur.com/g6sOADH

 

[Joseph Garcia]

Heat and an impact wrench (if you can get one to fit in that space).