Tubeless tire is deflated but having no luck getting the tire iron under the bead to fulcrum it up to begin the process - do bike shops have a special tool , is there a trick to it ? - any advise appreciated .
If you have a C clamp, or you can buy one, they're cheap, they look like this:
Note the distance from the screw area to the inside of the C and make sure you measure your tire so the C clamp you buy will fit. Remove the Presta valve core to make sure all the air gets out. Then place the ends of the clamp on the sidewalls then slowly tighten the clamp making sure you don't damage the rim of course. The squeezing in of the clamp should break the bead loose. A table top Vise can do the same thing.
When the sidewalls squeeze inward try getting a tire iron under the bead, if you still can't you'll have to break the bead off on both sides all the way around the rim/tire, then that should give you the room to put a tire iron under the tire, especially if the area you put the iron into you squeeze the tire into the center of the rim.