Hi all
I posted photos all of the same fig tree that has been growing in my yard for many years. I tried killing it like I did three other that were all growing in that area. I even used a drill to make holes into the toots  system applied root killing hormone a few times. I just could not kill it.

My intent now is since this thing doesn't die in my zone 5B area I want to try grafting on a cutting I just purchased. Now do I wait until green shoots can be seen before digging out a piece of that root ball then place that into a 5 gallon bucket and get it to grow an then try to graft on one of the black mission cuttings I just purchased?

Should I use an axe to cut just a portion of the rootball then dig out that area now or after new growth has started?
Photos attached all same plant. By the way all the years I had it it never produced even one fruit. Even when I had it protected way back when.
Thank you for any advice.
Lou