Lower the height of heels.

How much can be removed depends on 

1. the shape of the shoe and sole
2. flexibility of the sole and upper
3. whether they were too high or too low for the shape to start with

To get a sense of how they will feel with different amounts cut of.

1. put them both on 
2. stand next to a sturdy counter for support
3. put a book or piece of wood under the fronts

So if you think removing 10mm off would help ... stand the fronts on a 10mm thick book.

Plan B:

With the shoe on the counter, slide the heel down the side off the edge of the counter, 5, 10, 15mm. To help show what will happen to the toe.

• It goes up.
• Also the area where the ball of the foot contacts the ground may move.

As a general guide a soft floppy shoe will be ok to lower lots, like up to 50mm in some cases! Where as a stiff patent platform won't be so good. but generally you can always take 5-10mm off.

1 Get agreement with customer - mark back of left
2 Remove old heel
3 Grind lower - check angle
4 Put new heel on