You could....but Bam is right
Mild steel will work harden somewhat if you beat on it enough. But you will still only have a fairly weak blade that won't hold its edge, or retain its shape as well as something made of steel with a higher carbon content.
With cheap machetes at the prices they are, why do you want to make one out of inferior steel? Is it for the interest of making, or because you want to save money?
What sort of size machete did you want, what did you want to use it on?