Toilets, Sinks, Showers, Tubs and Disposals - PVC Closet Flange Too High

I removed a bathroom tile floor that (for some reason) had been installed on a 1-3/4" mortar bed. Home is built on a slab and the concrete floor has no imperfections and is perfectly level. Instead of going back in with a mortar bed or somehow raising the floor around the toilet, I'd prefer to drop the closet flange down if that's not too difficult. The line coming up through the floor is PVC and it's connected to a white PVC flange - I assume it's been put on with PVC cement or was all one piece when the slab was poured. I didn't attempt to turn it for fear of breaking something and having a real problem on my hands. Is there a way to cut off the pipe and put a new flange on that seats and seals (but is not cemented)? I'm sure I can get a hack saw blade in just below the bottom of the flange. Perhaps I should just call a plumber?

If you can look down into the flange, and the pipe turns right away, there is not much you can do without a special tool made to remove pvc inside a fitting. If there is some pipe, 8" or more, you could use an inside pipe cutter to cut the pipe and then make any adjustments needed. An inside pipe cutter is cheap and is used with a drill.

I think you said this was a slab. If it were the first floor with a basement below, this would be so much easier...