It is rusted, but how can I remove it with out braking the main pipe

LP

I'm not clear here? Do you have a cast iron flange attached to a cast iron pipe or a metal flange attached to PVC? If you have a metal ring attached to PVC, your answer is in post #6. If you have a cast iron flange then the job just got a little bigger... ;)

Back to you...

Mark

Secondary post on an old post from 2009. Please clarify what the issue is. .

Hi Lady and welcome to The Plumbing Page at AskMeHelpDesk.com You are responding to a 4 year old dead thread so I gave you one of your own. Please check the date before you post. Thanks,
Sure sounds like a cast iron flange secured by a lead and oakum caulked joint. I can instruct you on how to remove it but why go through all that hassle if it's only a broken slot. Pick up a flange repair kit, (see image) and save yourself time and money. Good luck, Tom