I have atorch so that is my first solution. Try this one on; we have anumber of large hawthorne tree stumps (3' dia). The roots never die, just keep sending up shoots. The new stuff is easy, just pull out. The roots can be oup to 4" diamete and down, they reach out 30-50 feet bin all directions about 6-12" below grade. I have grabbed the large end with a chain choked on and pulled ot 30 footers with teh drawbar. When tilling my garden spot for the first time (three of those stumps around it, I wrapped one around the axel till it would hold no more. The big end was 2' dia and that wood is very fiberous and tough, does not chip it tears. Took me an hour down in the damp sawing, pulling, turning the axel with a bar, and swearing a lot before I got them all out. Had to cut between each tine with 10 wraps or more. It kept winding until it tripped the slip clutch. Your rebar would take me 10 minutes or less if close to the shop which my garden plot is. Cutting, 1/2 minute the rest travel and set up/shutdown.
Ron