I’ve always said that you would need to bypass Hitler and go right to the root of the problem. Kill Karl Marx.
Or rather, the two Frenchmen who inspired Marx and Engels, Victor d’Hupay and Etienne Cabet.
Go back and stop the US from entering WW 1. Put US forces into Russia, after consulting with the Czar, to protect his family, and bolster Russia. Let France and Britain wipe each other off the map.
The Original Sin of this country, was tying ourselves to England. Without the US they are a cute little country like Ireland was. WE upset the balance of the world, because of Presidents around the turn of the 19th to 20th Century. We lost the battle on Congress controlling Treasury, Income tax et al. Hoover, Wilson and FDR in particular.