How do you calm the heat of chili powder?

If you have eaten chili and your mouth is too hot, then the best neutralizer is to use dairy products.

The molecule that causes the "heat" is Capsaicin.

Capsaicin selectively binds to a protein known as TRPV1 that resides on the membranes of pain and heat sensing neurons and is NOT washed off by water.

However the constituents in dairy (milk, cheese, yogurt etc) do have the property of displacing the Capsaicin.

However, the compound is not readily digested and may cause stomach cramps and a marked after burn on exit.

If the problem is external an oil based product followed by washing with a detergent is a good way to cleanse the affected area.