Assuming you mean for an AR? Easier to watch a quick youtube video then explain it here. Easy enough with maybe a dental pick to get the old rings off.
The smithing is not restricted to S&Ws. Check out some of the threads for examples.
The suggestion in post #2 still applies for your issue.
But this thread is very helpful for the the discussion of the issue first.
Removing the pressed in gas ring is most easily done by walking it out with a threading tap to bottom on after cutting a few threads in the ring, and 'walking' the ring out.
Place something round in the cyl bore that reaches to about the bottom of the ring for the tap to bear against as it's turned. Of course lubricate for this procedure.