: : The flange is installed inside the 4" PVC drain pipe. I'm worried about breaking the PVC pipe below the level of the slab if I try to chisel it out. I don't have a Ram-Bit. Is this something I can get at Home Depot?
: Not sure if HD sells it, a plumbing supply house will, call around. I'm not sure if it will even work in piping, it's used for drilling out the remainders of PVC piping that would be in a fitting. You may be able to use a Dremel tool to slice the piping from the inside and install a special PVC closet flange that is made to be inserted into 4" PVC. You may want to hire a plumber to remove or possibly repair the broken flange, there are kits available although I have never used one. Good Luck.
I would cut the top of the flange off flat and drill around the pipe, remove the concrete and install a 4" female flange on top of the tile.
Anchoring the flange to the floor is important. You can use an arrow head shaped glass cutting bit to drill through the tile without chipping it.