What I’m trying to ascertain is can Congress or the Executive Branch unilaterally cancel an election for President if the Constitution requires that it be conducted on a certain date and that the states conduct the election? I have a lot to learn about the Constitution, but it appears that the states may even have a Constitutional obligation to do so. While the election of other positions may be cancelled by or with the approval of the current Congress, the election of the President perhaps isn’t so easily cancelled?
Only if the Constitution is annulled due to war or some major disturbance can elections be canceled. In that case, the President is military dictator. He can hold elections again if the Constitution is ever restored.
Note that LBJ asked the NSC to explore this scenario in 1968 after the unpleasantness at the Democratic Convention in Chicago. He feared that the antiwar youth and Black Panthers might join forces and disrupt the elections via terrorism.