Manually Adjust Tax Rates

When I am editing and order in admin, I try to alter the tax rates to remove the tax below but it always reverts back to the tax rate set on the product.

In some instances even though the product is taxable, i need to remove it when going to certain countries.

Am I doing the right thing, by setting the 20% vat to 0% and clicking recalculate, because it still stays to 20%