I have a rough in bathroom that was done in 1968 for the homeowners to finish. Cast iron pipes for shower and toilet are about 4 in. out of floor. How do I go about cutting them to install a toilet and a shower? To be flush with the concrete floor.
Plumbing – How to cut 1968 cast iron rough sewage pipe
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Related Solutions
For cutting the pipe, go rent a chain pipe cutter (aka soil pipe cutter). It will make short work of the pipe and not be too messy. It will make a clean enough edge that a Fernco coupling (like you have a picture of) will work fine.
Obviously you will need to add some strapping to secure the horizontal run of iron pipe if you go this route because you don't want to put any extra strain on that rubber coupling.
I would not mess with trying to remove the flange. I think it will be easier to just cut the pipe.
One of these ironic things? ("American" Valve - Made in Taiwan...)
You should probably try to smooth the pipe out more - a lot can be done with a narrow strip of coarse sandpaper, 
wrapped around the pipe so you can "saw" it back and forth. You can also try really cranking on the hose clamps - if you're only using a screwdriver, you haven't really hit what they can do (but you have to maintain some sense of proportion once you switch to using a socket and ratchet on them, or you'll find the breaking point.)
For sheer desperation, I'm not sure if silicone or beeswax (from a toilet seal ring, of course) would be the better desperation move. With kitchen waste it could get too hot for beeswax.
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Best Answer
Usually, the easiest way to cut cast iron pipe is with a snap cutter, but I don't think you could cut it completely flush with one. A sawzall with a long diamond tip blade might work for you. A diamond wheel in an angle grinder is another possibility. Alternatively, you could frame a wood floor to the height of your pipes.