Most turning tools use a tapered tang to secure them in the handle. Meaning that there is usually not any mechanical connection like a nut or flare that makes it impossible to remove. Note, I said MOST, you may have one of the minority. But unless there is a metal end cap on the butt of the tool, your pretty safe to assume it's just held in with glue and/or was pressed in at the factory. If the steel is not important, the simplest thing would be to clamp the blade in a vise, and heat it close to the handle with a torch till the glue releases and you can pull the handle off. If the tool has a metal ferule or cap on the blade end, it is usually just there to keep the wood from splitting, not to hold the blade in, and the tang should come out through it.
Some very old tools had the tang "burned in" or heated red hot then pressed into the handle with no glue. If you have one of these it may take a lot more heat to loosen it up. One option is to heat it up to expand it, then let it cool and shrink. a couple of cycles of this may loosen it up enough that you can clamp the blade in a vise and wrestle the handle off.
A purely mechanical method is to use a pair of slotted wedges (unless it's a bowl gouge where the blade is the same diameter the full length. But if the blade flares, you can cut some wedges from some scrap hardwood and cut a slot down the middle of each, then insert them between the handle and the flare in the blade. as you drive them together from both sides, they will push the blade out of the handle.
If none of the above work, take a picture of the item in question and I'll see if something else comes to mind.