11 April 1976 is generally accepted as the day Steve Wozniak built the Apple-I. To the orthodoxy that Wozniak was Apple’s inhouse inventor and Steve Jobs the inhouse marketer, the Apple-I brings two quirks.
First, Wozniak and not Jobs set the retail of $666.66 because he liked repeating digits and because it was a one-third markup on the $500 wholesale.
Secondly, what to do when the help desk is swamped. By 1977, Apple II had been released and calls were handled by everyone in engineering and sometimes by production line technicians. But the Apple-I calls still had to go to Wozniak.
Here Jobs and Apple the marketer came into their own. They worked to convert Apple-1 owners into Apple II owners with Jobs insisting that any intelligent person would obviously want to upgrade to an Apple II.
History does not recall who decided to delete the hyphen in the upgrade.