Changing a pair of shoes

I love the style of my pink high heels, but I’ve found that I can’t really wear them for more than 10 minutes at a time. I’m contemplating on shortening the heel a bit myself. I have the tools and skills to do this, but I am not sure if … Will it break the warranty for the rest of the shoe? Will it create balance problems for the shoe? Have anyone else done something similar to their shoes?