It isn't. It's false information perpetuated by Wikipedia and the Internet now. It was a trivia question in a game (The D Show) made years after the movie by a third party (for Disney Interactive-but no one with actual Archives access was involved) which inserted the question as a joke and homage to He-Man. The joke being that Prince Adam was lame until he transforms into something cooler.
Thanks to an answers.yahoo answer the information has now been falsely attributed to Dave Smith. But no one can cite anything except Yahoo answer as the source for the info.
(The fact that if you consult Smith's Encyclopedia and the name isn't in there doesn't seem to deter anyone.)
He is merely "The Prince".