Zuzu

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Race Change only covers Race + Character alteration. But keep in mind, you cannot race change if you're a class that the race you want to change to does not have. I.E: Changing from Lyn Summoner to Gon is not possible. But changing from Gon Force Master to Yun is possible. There's no class change voucher.

Have you tried dragging it out of your inventory and deleting it that way? Or selling it to the NPC?