Hi,

Can heal height, say 3 inches + be cut down to a 21/2 or 2 inch heal
by a cobbler  or shoe repair shop?

I would assume not.  If you hold a shoe with a 3" heel in the air,
note that the back of the heel is 3" higher than the toe of the shoe. 
That is th shape of the shoe.  The heel is there to ensure that when
you place weight on it, the heel stays at a 3" height.  If you cut the
heel down to 2", you haven't changed the shape of the shoe.  The heel
is still 3" higher than the toe, but when you wear the shoe, the heel
is not supported at 3".  So it will collapse by an inch every time you
take a step.

Back in the '60s, I asked a shoe repair shop about this, and was told
that it was not practical to cut down heels or to put shorter heels on
a high-heeled shoe. The angle of the shoe's sole would be all wrong
afterward, and the shoe would be horribly uncomfortable to walk in.