Repeal the 16th amendment, which authorizes a federal income tax and was enacted in 1913. Replace it with a flat National sales tax, which would scale in proportion to income.
A national sales tax would also create taxation on people who do not pay taxes, such as drug dealers, illegal immigrants, and some of the very rich.
A national sales tax would also pave the way to phase out the Internal Revenue Service and the tax code, which are so convoluted no human could ever fully understand them.