Adding a Hero to a map

Is there any easy way to add a hero to a map? Like, for example, if I had a custom map, and wanted to add a Wizard as a custom hero for the Night Elves.

What I did is add a custom Night Elf Hero with the unit editor, and I deleted the Demon Hunter (Because he isn't in the map), and set the Wizard's settings all up, but now when I try to play the map the Wizard can't be trained at the Altar and the Demon Hunter is still available (Even though I thought I deleted him). Anyone know what I did wrong? (I copied most of the settings from the Human Archmage, but changed some health, mana, and abilities)

Edit the building. Delete demon hunter and add the mage.