I’m trying to replace the seal on my toilet. When I lifted the toilet off the floor the flange stayed on the bottom of the commode. I cannot figure out how to remove the flange.I’ve tried pulling and twisting with no success. How can I remove the flange?
Brute force. That's the answer. A flat head screwdriver and a hammer? IDK -- you pick your favorite tools, just try not to break the toilet.
The rest is speculation.
I see a flange extender. I don't see any wax residue. Someone used a flange extension, did not secure it to the floor, and used silicone or glue to attach it to the toilet. Maybe there was wax between the flange and the extension? Did you clean it off? REALLY really well?
Anyway you just need to rip that thing off. Hopefully it's silicone, once you get it started it'll peel off. If it's glue you might need to chip off bits of plastic one tiny shard at a time with a wood chisel. Or just get a new toilet. You don't actually have to clean it up perfectly .... the new wax ring will make a good seal around any small bits left over.